View source for East–West Schism

{{Short description|Break of communion between the Western and Eastern churches}}
{{About||other schisms between the Church of Rome and the Church of Constantinople|Rome–Constantinople schism (disambiguation)|the 1376–1419 schism in the Catholic Church, which is sometimes also called the Great Schism|Western Schism}}

{{Infobox event
| image = Great_Schism_with_former_borders_(1054).png
| caption = The divided church immediately following the schism
| type = [[Schism#Christianity|Christian schism]]
| cause = {{ubli|[[Eastern Orthodox – Roman Catholic ecclesiastical differences|Ecclesiastical differences]]|[[Theological differences between the Catholic Church and the Eastern Orthodox Church|Theological and liturgical disputes]]}}
| date = 16 July 1054 – present<br />({{Age in years, months, and days|year=1054|month=07|day=16}})
| participants = {{ubli|[[Pope]] [[Leo IX]] | [[Ecumenical Patriarch]] [[Michael I Cerularius]]}}
| also_known_as = {{ubli|Great Schism|Schism of 1054| Eastern Schism|Latin Schism}}
| outcome = Split of the two churches into the modern-day [[Roman Catholic Church|Catholic Church]] (from which the [[Protestant Church]] later broke off) and [[Eastern Orthodox Church]] to this day
}}

{{Historical Christian theology}}
{{Catholicism–Eastern Orthodoxy sidebar}}

The '''East–West Schism''', also known as the '''Great Schism''' or the '''Schism of 1054''', is the break of [[communion (Christian)|communion]] between the [[Catholic Church]] and the [[Eastern Orthodox Church]] since 1054.{{sfn|Cross|Livingstone|2005|p=706}} A series of [[Eastern Orthodox – Roman Catholic ecclesiastical differences|ecclesiastical differences]], [[Theological differences between the Catholic Church and the Eastern Orthodox Church|theological disputes]] and geopolitical tensions between the [[Greek East and Latin West]] preceded the formal split in 1054.{{sfn|Cross|Livingstone|2005|p=706}}{{sfn|D'Agostino|2008}}{{sfn|Bayer|2004}} Prominent among these were the [[procession of the Holy Spirit]] ({{lang|la|[[Filioque]]}}), whether [[leavened]] or [[unleavened bread]] should be used in the [[Eucharist]],{{Efn | A late-11th-century pamphlet, ''Against the Franks'',{{sfn|Palatianos|n.d.}} that was falsely attributed to [[Photios I of Constantinople]] lists this as the second point, right after the {{lang|la|Filioque}}.{{sfn|Hergenröther|1869|pp=62–71}}{{sfn|Beck|1982|pp=245–247}}}} [[iconoclasm]], the coronation of [[Charlemagne]] as [[Holy Roman Emperor|emperor of the Romans]] in 800, the [[pope]]'s claim to [[Papal supremacy|universal jurisdiction]], and the place of the [[See of Constantinople]] in relation to the [[pentarchy]].{{sfn|Lembke|2010}} Although 1054 has become conventional, various scholars have proposed different dates for the Great Schism, including 1009,<ref>John S. Romanides, [http://www.romanity.org/htm/rom.12.en.orthodox_heterodox_dialogues.01.htm "Orthodox-Heterodox Dialogues and The World Council of Churches"], Lecture at St. Vladimir's Seminary 23 May 1980 in honor of Father Georges Florovsky</ref> 1204,<ref name="Haddad 2002">Robert M. Haddad, "The Stations of the filioque", ''St Vladimir's Theological Quarterly'' 46:2 (2002)</ref> 1277,<ref>James Edward Cowell Welldon, ''The Revelation of the Holy Spirit'', (Macmillan and Company, 1902) p. 260.</ref> and 1484.<ref>Kimberly Hope Belcher, et al. "One Baptism—One Church?
A History and Theology of the Reception of Baptized Christians," Liturgical Press, 2024, pp. 95-97.</ref>

The first action that led to a formal schism occurred in 1053 when Patriarch [[Michael I Cerularius]] of Constantinople ordered the closure of all Latin churches in [[Constantinople]].{{sfn|Dragani|2005|p=44}}{{sfn|Bihlmeyer|Tüchle|1967|p=102}}{{sfn|Bury|1923|p=267}} In 1054, the [[papal legate]] sent by [[Leo IX]] travelled to Constantinople to deny Cerularius the title of "[[ecumenical patriarch]]" and insist that he recognize the pope's claim to be the head of all of the churches,{{sfn|Cross|Livingstone|2005|p=706}} and to seek help from the [[Byzantine emperor]], [[Constantine IX Monomachos]], in view of the [[Norman conquest of southern Italy]], and to respond to [[Leo of Ohrid]]'s attacks on the use of unleavened bread and other Western customs,{{sfn|Siecienski|2010|p=113}} attacks that had the support of Cerularius.{{sfn|Bayer|2004|p=80}} When the leader of the legation, Cardinal [[Humbert of Silva Candida]], learned that Cerularius had refused to accept the demand, he [[Excommunication (Catholic Church)|excommunicated]] him, and in response Cerularius excommunicated Humbert and the other legates.{{sfn|Cross|Livingstone|2005|p=706}} 

The validity of the Western legates' act is doubtful because Pope Leo had died and Cerularius' excommunication only applied to the legates personally.{{sfn|Cross|Livingstone|2005|p=706}} Still, the Church split along doctrinal, theological, linguistic, political, and geographical lines, and the fundamental breach has never been healed: each side occasionally accuses the other of committing [[Heresy in Christianity|heresy]] and of having initiated the schism. Reconciliation was made increasingly difficult in the generations that followed; events such as the Latin-led [[Crusades]], though originally intended to aid the Eastern Church, only served to further tension. The [[Massacre of the Latins]] in 1182 greatly deepened existing animosity and led to the West's retaliation via the [[Sack of Thessalonica (1185)|Sacking of Thessalonica in 1185]], the [[Siege of Constantinople (1204)|pillaging of Constantinople]] during the [[Fourth Crusade]] in 1204, and the imposition of [[Patriarch#Other historical Latin patriarchates|Latin patriarchs]].{{sfn|Cross|Livingstone|2005|p=706}} The emergence of competing Greek and [[Latin Church|Latin]] hierarchies in the [[Crusader states]], especially with two claimants to the patriarchal sees of Antioch, Constantinople, and Jerusalem, made the existence of a schism clear.{{sfn|Nichols|2010|p=281}} Several attempts at reconciliation did not bear fruit.

In 1965, [[Pope Paul VI]] and Ecumenical Patriarch [[Athenagoras I]] nullified the [[anathema]]s of 1054,{{sfn|Cross|Livingstone|2005|p=706}} although this merely as a gesture of goodwill and not constituting any sort of reunion. The absence of full communion between the Churches is even explicitly mentioned when the Code of Canon Law gives Catholic ministers permission to administer the sacraments of penance, the Eucharist, and the anointing of the sick to members of eastern churches such as the Eastern Orthodox Church (as well as the [[Oriental Orthodox]] churches and the [[Church of the East]]) and members of western churches such as the [[Old Catholic Church]], when those members spontaneously request these.<ref name="CCEO#844" /> Contacts between the two sides continue. Every year a delegation from each joins in the other's celebration of its patronal feast, [[Feast of Saints Peter and Paul|Saints Peter and Paul]] (29 June) for [[Holy See|Rome]] and [[Feast of Saint Andrew|Saint Andrew]] (30 November) for Constantinople, and there have been several visits by the head of each to the other. The efforts of the ecumenical patriarchs towards reconciliation with the Catholic Church have often been the target of sharp internal criticism.{{sfn|Anon.|2001|p=149}}

==Differences underlying the schism==
[[Jaroslav Pelikan]] emphasizes that "while the East–West schism stemmed largely from political and ecclesiastical discord, this discord also reflected basic theological differences". Pelikan further argues that the antagonists in the 11th century inappropriately exaggerated their theological differences, whereas modern historians tend to minimize them. Pelikan asserts that the documents from that era evidence the "depths of intellectual alienation that had developed between the two sections of Christendom." While the two sides were technically more guilty of schism than heresy, they often charged each other with allegations of blasphemy. Pelikan describes much of the dispute as dealing with "regional differences in usages and customs", some of which were adiaphorous (i.e. neither commanded nor forbidden). However, he goes on to say that while it was easy in principle to accept the existence of adiaphora, it was difficult in actual practice to distinguish customs which were innocuously adiaphoric from those that had doctrinal implications.{{sfn|Pelikan|1971|p=170}}

===Ecclesiological disputes===
{{See also|Ecclesiology}}

Philip Sherrard, an [[Eastern Orthodox theologian]], asserts that the underlying cause of the East–West schism was and continues to be "the clash of these two fundamentally irreconcilable ecclesiologies". Roger Haight characterizes the question of episcopal authority in the Church as "acute" with the "relative standings of Rome and Constantinople a recurrent source of tension". Haight characterizes the difference in ecclesiologies as "the contrast between a pope with universal jurisdiction and a combination of the patriarchal superstructure with an episcopal and synodal communion ecclesiology analogous to that found in [[Cyprian]]".{{sfn|Haight|2004|p=289}} However, [[Nicholas Afanasiev]] has criticized both the Catholic and Orthodox churches for "subscribing to the universal ecclesiology of St. Cyprian of Carthage according to which only one true and universal church can exist".{{sfn|Doyle|Furry|Bazzell|2012|p=311}}

Another point of controversy was [[Clerical celibacy (Catholic Church)|celibacy among Western priests]] (both monastic and parish), as opposed to the Eastern discipline whereby parish priests could be married men. However, the Latin church has always had some priests who were legally married. They have been a small minority since the 12th century.{{citation needed|date=December 2023}}

====Ecclesiological structure====
{{See also|Primacy of the Roman Pontiff|Eastern Orthodox Church organization}}

There are several different ecclesiologies: "communion ecclesiology", "eucharistic ecclesiology", "baptismal ecclesiology", "trinitarian ecclesiology", "kerygmatic theology".{{sfn|Millet|2010|pp=43–44}} Other ecclesiologies are the "hierarchical-institutional" and the "organic-mystical",{{sfn|Volf|1998|p=42}} and the "congregationalist".{{sfn|Volf|1998|p=44}}

The Eastern Churches maintained the idea that every local city-church with its bishop, presbyters, deacons, and people celebrating the [[eucharist]] constituted the whole church. In this view called eucharistic ecclesiology (or more recently holographic ecclesiology), every bishop is [[Saint Peter]]'s successor in his church ("the Church"), and the churches form what [[Eusebius of Caesarea|Eusebius]] called a common union of churches. This implied that all bishops were ontologically equal, although functionally particular bishops could be granted special privileges by other bishops and serve as [[Metropolitan bishop|metropolitans]], [[archbishops]] or [[patriarch]]s. Within the Roman Empire, from the time of Constantine to the fall of the empire in 1453, universal ecclesiology, rather than eucharistic, became the operative principle.{{sfn|Cleenewerck|2007|pp=107–108, 209ff.}}{{sfn|Ferencz|2006|pp=21–22}}

The view prevailed that, "when the Roman Empire became Christian the perfect world order willed by God had been achieved: one universal empire was sovereign and coterminous with it was the one universal church".{{sfn|Becchio|Schadé|2006|loc=§8}} Early on, the Roman Church's ecclesiology was universal, with the idea that the Church was a worldwide organism with a divinely (not functionally) appointed center: the Church/Bishop of Rome. These two views are still present in modern Eastern Orthodoxy and Catholicism and can be seen as foundational causes for the schisms and Great Schism between East and West.

The Orthodox Church does not accept the doctrine of Papal authority set forth in the Vatican Council of 1870, and taught today in the Catholic Church.{{sfn|Ware|1963|p=27}} The Orthodox Church has always maintained the original position of [[collegiality]] of the bishops resulting in the structure of the church being closer to a [[Confederation|confederacy]]. The Orthodox have [[synod]]s where the highest authorities in each Church community are brought together, but, unlike the Catholic Church, no central individual or figure has the absolute and infallible last word on church doctrine. In practice, this has sometimes led to divisions among Greek, Russian, Bulgarian and Ukrainian Orthodox churches, as no central authority can serve as an arbitrator for various internal disputes.{{citation needed|date=December 2023}}

Starting from the second half of the 20th century, eucharistic ecclesiology is upheld by Catholic theologians. [[Henri de Lubac]] writes: "The Church, like the Eucharist, is a mystery of unity – the same mystery, and one with inexhaustible riches. Both are the body of Christ – the same body."{{sfn|McPartlan|1995|p=xv}} [[Joseph Ratzinger]] called eucharistic ecclesiology "the real core of Vatican II's ([[Second Vatican Council]]) teaching on the cross".{{sfn|Volf|1998|p=42}} According to Ratzinger, the one church of God exists in no other way than in the various individual local congregations.{{sfn|Volf|1998|p=43}} In these the eucharist is celebrated in union with the Church everywhere.{{sfn|Garuti|2004|p=66|loc=Note 276}} Eucharistic ecclesiology led the council to "affirm the theological significance of the local church. If each celebration of the Eucharist is a matter not only of Christ's sacramental presence on the altar but also of his ecclesial presence in the gathered community, then each local eucharistic church must be more than a subset of the universal church; it must be the body of Christ 'in that place'."{{sfn|Gaillardetz|2006|p=46}}

The ecclesiological dimension of the East–West schism revolves around the authority of bishops within their dioceses{{sfn|Cleenewerck|2007|p=22}} and the lines of authority between bishops of different dioceses. It is common for Catholics to insist on the [[Papal primacy|primacy of Roman and papal authority]] based on patristic writings and conciliar documents.{{sfn|Shaw|2000|p=40}}

====Papal privilege and authority====
{{See also|Pseudo-Isidore|Donation of Constantine}}
The Catholic Church's current official teachings about papal privilege and power that are unacceptable to the Eastern Orthodox churches are the dogma of the [[Papal infallibility|pope's infallibility]] when speaking officially "from the chair of Peter ({{lang|la|ex cathedra Petri}})" on matters of faith and morals to be held by the whole Church, so that such definitions are irreformable "of themselves, and not by the consent of the Church" ({{lang|la|ex sese et non-ex consensu ecclesiae}})<ref name="VaticanI" /> and have a binding character for all (Catholic) Christians in the world; the pope's direct episcopal jurisdiction over all (Catholic) Christians in the world; the pope's authority to appoint (and so also to dismiss){{Citation needed|date=January 2009|reason=Perhaps}} the bishops of all (Catholic) Christian churches except in the territory of a patriarchate;<ref name="CCEO#181" /> and the affirmation that the legitimacy and authority of all (Catholic) Christian bishops in the world derive from their union with the Roman see and its bishop.{{Citation needed|date=January 2009|reason=Perhaps, but https://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19641121_lumen-gentium_en.html ''Lumen gentium'' says: [The pastoral office or the habitual and daily care of their sheep is entrusted to them (the bishops) completely; nor are they to be regarded as vicars of the Roman Pontiffs, for they exercise an authority that is proper to them, and are quite correctly called 'prelates', heads of the people whom they govern.]}}

Principal among the ecclesiastical issues that separate the two churches is the meaning of papal primacy within any future unified church. The Orthodox insist that it should be a "primacy of honor", and not a "primacy of authority",{{sfn|Ware|1963}} whereas the Catholics see the pontiff's role as required for its exercise of power and authority, the exact form of which is open to discussion with other Christians.{{efn|In 1995, John Paul II wrote: "With the power and the authority without which such an office would be illusory, the Bishop of Rome must ensure the communion of all the Churches." He invited "Church leaders and their theologians to examine with me in a patient and fraternal dialogue on this subject, a dialogue in which, leaving useless controversies behind, we could listen to one another, keeping before us only the will of Christ for his Church and allowing ourselves to be deeply moved by his plea 'that they may all be one ... so that the world may believe that you have sent me{{'"}}.{{sfn|John Paul II|1995|loc=para 96}} The Ravenna document of 13 October 2007<ref name="orthodoxeurope.org" /> is one response to this invitation.}} According to Eastern Orthodox belief, the test of [[catholicity]] is adherence to the authority of ''[[Religious text#Christianity|Scripture]]'' and then by the ''[[Holy Tradition]]'' of the church. It is not defined by adherence to any particular [[Episcopal see|see]]. It is the position of the Orthodox Church that it has never accepted the pope as ''de jure'' leader of the entire church.

Referring to Ignatius of Antioch,{{sfn|Ignatius of Antioch|1846|p=116}} Carlton says:
{{Blockquote | Contrary to popular opinion, the word catholic does not mean "universal"; it means "whole, complete, lacking nothing." ... Thus, to confess the Church to be catholic is to say that She possesses the fullness of the Christian faith. To say, however, that Orthodox and Rome constitute two lungs of the same Church is to deny that either Church separately is catholic in any meaningful sense of the term. This is not only contrary to the teaching of Orthodoxy, it is flatly contrary to the teaching of the Roman Catholic Church, which considered itself truly catholic|source={{harvnb|Carlton|2007|p=22}} }}

The church is in the image of the [[Trinity]]{{sfn|Lossky|1976|p=176}} and reflects the reality of the incarnation.
{{Blockquote | The body of Christ must always be equal with itself&nbsp;... The local church which manifests the body of Christ cannot be subsumed into any larger organisation or collectivity which makes it more catholic and more in unity, for the simple reason that the principle of total catholicity and total unity is already intrinsic to it.|source={{harvnb|Sherrard|1996|p=15}}}}

===Theological issues===

{{Main|Theological differences between the Catholic Church and the Eastern Orthodox Church|Contra Errores Graecorum}}

The [[iconoclasm|iconoclast]] policy enforced by a series of decrees of Emperor [[Leo III the Isaurian]] in 726–729 was resisted in the West, giving rise to friction that ended in 787, when the [[Second Council of Nicaea]] reaffirmed that images are to be venerated but not worshipped. The [[Libri Carolini]], commissioned by [[Charlemagne]], criticized what a faulty translation gave as the council's decision, but their objections were rebutted by [[Pope Adrian I]].

From the Catholic Church's perspective, the ecclesiological issues are central, which is why they characterize the split between the two churches as a schism. In their view, the Eastern Orthodox are close to them in theology, and the Catholic Church does not consider the Eastern Orthodox beliefs to be heretical. However, from the perspective of Eastern Orthodox theologians, there are theological issues that run much deeper than just the theology around the [[Papal primacy|primacy of the Pope]]. In fact, this is in contrast to Catholics, who do not generally consider the Orthodox heretical and speak instead about the Eastern "schism".{{sfn|Fortescue|1912}}

In the Catholic Church, too, some writers may be found, who speak pejoratively about the Eastern Orthodox Church and its theology, but these writers are marginal.<ref name="Guimarães" />

The official view of the Catholic Church is the one expressed in the decree {{lang|la|[[Unitatis redintegratio]]}} of Vatican II:

{{Blockquote | In the study of revelation East and West have followed different methods, and have developed differently their understanding and confession of God's truth. It is hardly surprising, then, if from time to time one tradition has come nearer to a full appreciation of some aspects of a mystery of revelation than the other, or has expressed it to better advantage. In such cases, these various theological expressions are to be considered often as mutually complementary rather than conflicting. Where the authentic theological traditions of the Eastern Church are concerned, we must recognize the admirable way in which they have their roots in Holy Scripture, and how they are nurtured and given expression in the life of the liturgy. They derive their strength too from the living tradition of the apostles and from the works of the Fathers and spiritual writers of the Eastern Churches. Thus they promote the right ordering of Christian life and, indeed, pave the way to a full vision of Christian truth.<ref name="Unitatis Redintegratio" />}}

====Trinity====
{{See also|Filioque}}

Although the Western churches do not consider the Eastern and Western understanding of the [[Trinity]] to be radically different, Eastern theologians such as [[John Romanides]] and Michael Pomazansky argue that the {{lang|la|Filioque}} clause is symptomatic of a fatal flaw in the Western understanding, which they attribute to the influence of Augustine and, by extension, to that of [[Thomas Aquinas]].{{sfn|Pomazansky|1984|p=14|loc=[http://www.intratext.com/IXT/ENG0824/_P14.HTM On the procession of the Holy Spirit]}}<ref name="Romanides_Filioque" /><ref name="Franks" />

{{lang|la|Filioque}}, Latin for "and (from) the Son", was added in Western Christianity to the Latin text of the [[Nicene-Constantinopolitan Creed]], which also varies from the original Greek text in having the additional phrase {{lang|la|Deum de Deo}} (God from God){{sfn|Bindley|1980|p=78}}{{sfn|Schaff|1877|p=24|loc=§ 8. The Nicene Creed}} and in using the singular "I believe" ({{langx|la|Credo}}, {{langx|grc|Πιστεύω}}) instead of the original "We believe" ({{langx|grc|Πιστεύομεν}}),{{sfn|Schaff|1877|p=24|loc=§ 8. The Nicene Creed}} which the [[Oriental Orthodox Churches]] and the [[Church of the East]] also preserve.{{efn|
*Oriental Orthodox churches:
** [[Armenian Apostolic Church]]<ref name="armenianchurchlibrary.com" />
** [[Coptic Orthodox Church of Alexandria]]<ref name="saintmaryhouston.org" />
** [[Eritrean Orthodox Tewahedo Church]]
** [[Ethiopian Orthodox Tewahedo Church]]<ref name="EOTC" />
** [[Malankara Syriac Orthodox Church]]<ref name="sor.cua.edu" />
** [[Syriac Orthodox Church]]
*Churches belonging to the Church of the East tradition:
**[[Assyrian Church of the East]]<ref name="assyrianchurch.org.au" />
**[[Ancient Church of the East]]}}

{{lang|la|Filioque}} states that the Holy Spirit proceeds from the Son as well as from the Father, a doctrine accepted by the [[Catholic Church]],{{sfn|Catholic Church|1994|p=65|loc=para 246}} by [[Anglicanism]]<ref name="victorianweb.org" /> and by [[Protestantism|Protestant churches]] in general.{{efn|Protestant churches:
* [[Lutheranism]]<ref name="bookofconcord.org" />
* [[Presbyterianism]]<ref name="saintandrewsrpcga.org" />
* [[Methodism]]<ref name="umc" /><!--Anglicanism??-->}}
Christians of these groups generally include it when reciting the Nicene Creed. Nonetheless, these groups recognize that {{lang|la|Filioque}} is not part of the original text established at the [[First Council of Constantinople]] in 381,{{sfn|Catholic Church|1994|p=65|loc=para 247}} and they do not demand that others too should use it when saying the Creed.<ref name="kaldu.org" /> The Catholic Church does not add the phrase corresponding to {{lang|la|Filioque}} ({{lang|grc|καὶ τοῦ Υἱοῦ}}) to the Greek text of the Creed, including in the [[Roman Rite]] of [[Latin Church]] Catholics.<ref name="PCPCU" />

At the [[Fourth Council of Constantinople (Eastern Orthodox)|879–880 Council of Constantinople]] the Eastern Orthodox Church anathematized the {{lang|la|Filioque}} phrase, "as a novelty and augmentation of the Creed", and in their 1848 encyclical the Eastern Patriarchs spoke of it as a heresy.<ref name="encyc1848" /> It was qualified as such by some of the Eastern Orthodox Church's saints, including [[Photios I of Constantinople]], [[Mark of Ephesus]], and [[Gregory Palamas]], who have been called the Three Pillars of Orthodoxy. The Eastern church believes by the Western church inserting the {{lang|la|Filioque}} unilaterally (without consulting or holding council with the East) into the Creed, that the Western Church broke communion with the East.<ref name="r1">Quoting [[Aleksey Khomyakov]] on the Filioque and economy of the Eastern Churches and Roman Catholicism {{harvnb|Lossky|1969|p=87}}</ref>

Eastern Orthodox theologians such as [[Vladimir Lossky]] criticize the focus of Western theology of God in "God in uncreated essence" as misguided, which he alleges is a [[modalism|modalistic]] and therefore a speculative expression of God that is indicative of the [[Sabellianism|Sabellian]] heresy.{{sfn|Lossky|1976}} Eastern Orthodox theologian [[Michael Pomazansky]] argues that, in order for the Holy Spirit to proceed from the Father and the Son in the Creed, there would have to be two sources in the deity (double procession), whereas in the one God there can only be one source of divinity, which is the Father hypostasis of the Trinity, not God's essence per se.{{sfn|Pomazansky|1984|p=14|loc=[http://www.intratext.com/IXT/ENG0824/_P14.HTM "On the procession of the Holy Spirit"]}} In contrast, Bishop [[Kallistos Ware]] suggests that the problem is more in the area of semantics than of basic doctrinal differences:
{{Blockquote|The {{lang|la|Filioque}} controversy which has separated us for so many centuries is more than a mere technicality, but it is not insoluble. Qualifying the firm position taken when I wrote ''The Orthodox Church'' twenty years ago, I now believe, after further study, that the problem is more in the area of semantics than in any basic doctrinal differences.|author=Bishop Kallistos Ware, Diakonia|source={{harvnb|Zoghby|1992|p= 43}} }}

====Experience of God versus scholasticism====
{{Further|Hesychasm}}

Lossky argues the difference in East and West is because of the Catholic Church's use of pagan metaphysical philosophy (and scholasticism) rather than actual experience of God called {{lang|grc-Latn|theoria}}, to validate the theological dogmas of Catholic Christianity. For this reason, Lossky states that Eastern Orthodox and Catholics have become "different men".{{sfn|Lossky|1976|p=21}} Other Eastern Orthodox theologians such as [[John Romanides|Romanides]]<ref name="Franks" /> and Metropolitan [[Hierotheos (Vlachos)|Hierotheos]] of [[Nafpaktos]] have made similar pronouncements.{{sfn|Vlachos|1994|loc=Ch. VI}} According to the Orthodox teachings, {{lang|grc-Latn|theoria}} can be achieved through ascetic practices like [[hesychasm]], which was condemned as a heresy by [[Barlaam of Seminara]].

Eastern Orthodox theologians charge that, in contrast to [[Eastern Orthodox theology]], western theology is based on philosophical discourse which reduces humanity and nature to cold mechanical concepts.{{sfn|Pomazansky|1984|p=2|loc=[http://www.intratext.com/IXT/ENG0824/_P2N.HTM Philosophy and Theology]}}

{{Blockquote|Roman Catholicism rationalizes even the sacrament of the Eucharist: it interprets spiritual action as purely material and debases the sacrament to such an extent that it becomes in its view a kind of atomistic miracle. The Orthodox Church has no metaphysical theory of Transsubstantiation, and there is no need of such a theory. Christ is the Lord of the elements and it is in His power to do so that 'every thing, without in the least changing its physical substance' could become His Body. Christ's Body in the Eucharist is not physical flesh.|source={{harvnb|Lossky|1969|p= 87}} }}

Eastern Orthodox theologians argue that the mind (reason, rationality) is the focus of Western theology, whereas, in Eastern theology, the mind must be put in the heart, so they are united into what is called [[nous]]; this unity as heart is the focus of Eastern Orthodox Christianity,<ref name="acrod.org" /> involving the unceasing [[prayer of the heart]]. In Orthodox theology, in the Eastern [[ascetic]] traditions, one of the goals of ascetic practice is to obtain sobriety of consciousness, awakeness ([[nepsis]]). For humankind, this is reached via the healing of the whole person, encompassing the soul/heart. When a person's heart is reconciled with their mind, this is referred to as a healing of the nous or the "eye, focus of the heart or soul".<ref name="Neptic Monasticism" />{{sfn|Vlachos|1994|loc=Ch. III}}

Part of this process is the healing and reconciliation of humankind's [[reason]] ({{lang|grc-Latn|logos}} or {{lang|grc-Latn|dianoia}}) with the heart or soul.{{sfn|Romanides|2008|pp=19–23}} While the human spirit and body are energies vivified by the soul, Orthodoxy teaches sin, suffering and sorrow are caused by the heart and mind being in conflict.{{sfn|Vlachos|1994|loc=Ch. III}} According to Orthodox theology, a lack of [[Nous|noetic]] understanding (sickness) can be neither circumvented nor satisfied by rational or discursive thought (i.e. [[systematization]]).<ref name="Neptic Monasticism" /> Denying the needs of the human heart (the needs of the soul) is seen to cause various negative or destructive manifestations such as addiction, atheism and evil thoughts.{{sfn|Romanides|1983|p=[http://romanity.org/htm/rom.19.en.jesus_christ_the_life_of_the_world.01.htm#s3 232]}}{{sfn|Vlachos|1993|loc=[https://web.archive.org/web/20090326044427/http://www.pelagia.org/htm/b05.en.the_illness_and_cure_of_the_soul.02.htm#Fall The Fall of man]}} A cleaned, healed or restored ''nous'' creates the condition of [[sobriety]], or nepsis of the mind.

====Uncreated light====
{{main|Kollyvades Movement}}
{{See also|Tabor light|Nicholas Kabasilas}}
Orthodox theologians assert that the theological division of East and West culminated into a direct theological conflict known as the [[Hesychasm controversy]] during several councils at Constantinople between 1341 and 1351. They argue that this controversy highlighted the sharp contrast between what is embraced by the Catholic Church as proper (or orthodox) theological dogma and how theology is validated by the Eastern Orthodox. The essence of the disagreement is that in the East a person cannot be a true theologian or teach the knowledge of God without having experienced God, as defined as the vision of God ({{lang|grc-Latn|theoria}}). At the heart of the issue was the teaching of the [[Essence-Energies distinction]]s (which states that while creation can never know God's uncreated essence, it can know his uncreated energies) by Gregory Palamas.

====Original sin, free will, and the Immaculate Conception====

=====Augustine's doctrine of original sin=====
Some Eastern Orthodox polemicists claim that Eastern Orthodox do not accept [[Augustine of Hippo|Augustine]]'s teaching of [[original sin]]. His interpretation of [[ancestral sin]] is rejected in the East as well. Nor is Augustine's teaching accepted in its totality in the West.<ref name="Neuro" /> The Catholic Church rejects [[traducianism]] and affirms [[creationism (soul)|creationism]] of the soul. Its teaching on original sin is largely based on but not identical with that of Augustine, and is opposed to the interpretation of Augustine advanced by [[Martin Luther]] and [[John Calvin]]. Its teaching departs from Augustine's ideas in some respects.<ref name="Neuro" />{{sfn|Hughes|n.d.}}

Another Eastern Orthodox view is expressed by [[Christos Yannaras]], who described Augustine as "the fount of every distortion and alteration in the Church's truth in the West".{{sfn|Giannaras|1984|p=151}} This view is ahistorical. In fact, Augustine's teaching on original sin was solemnly affirmed by the ecumenical Council of Ephesus,<ref>{{cite web|date=2016-06-20|title=Original Sin and Orthodoxy: Reflections on Carthage – Orthodoxy and Heterodoxy|url=https://blogs.ancientfaith.com/orthodoxyandheterodoxy/2013/08/22/original-sin-and-orthodoxy-reflections-on-carthage/|access-date=2021-06-13|archive-url=https://web.archive.org/web/20160620105310/https://blogs.ancientfaith.com/orthodoxyandheterodoxy/2013/08/22/original-sin-and-orthodoxy-reflections-on-carthage/|archive-date=20 June 2016}}</ref><ref>{{cite web|title=Original Sin and Ephesus: Carthage's Influence on the East – Journal|date=4 January 2019 |url=https://journal.orthodoxwestblogs.com/2019/01/04/original-sin-and-ephesus-carthages-influence-on-the-east/|access-date=2021-06-13|language=en-US}}</ref> and the ecumenical [[Second Council of Constantinople]] numbered Saint Augustine among the great doctors of the Church, alongside [[Athanasius of Alexandria]], [[Hilary of Poitiers]], [[Basil of Caesarea]], [[Gregory of Nazianzus]], [[Gregory of Nyssa]], [[St. Ambrose]], Theophilus, [[John Chrysostom]], [[Cyril of Alexandria]], and [[Pope Leo the Great]].<ref>{{cite web|first=Philip |last=Schaff |id=NPNF2-14 |title=The Seven Ecumenical Councils |website=Christian Classics Ethereal Library|url=https://www.ccel.org/ccel/schaff/npnf214.xii.iv.html|access-date=2021-06-13}}</ref> The late modern denial by some Eastern Orthodox writers of the supposedly "Western" teaching on original sin is regarded by some traditionalist Eastern Orthodox as a form of [[Modernist Christianity|modernism]].<ref>{{Cite web|title=Metropitan Ephraim and Original Sin |url=http://www.orthodoxchristianbooks.com/articles/278/metropolitan-ephraim-original-sin/|access-date=2021-06-13|website=www.orthodoxchristianbooks.com}}</ref><ref>{{cite web|title=Romanides on Original Sin |url=http://www.orthodoxchristianbooks.com/articles/399/romanides-original-sin/|access-date=2021-06-13|website=www.orthodoxchristianbooks.com}}</ref>

===== Eastern Orthodox teaching on original sin =====
What the Eastern Orthodox Church accepts is that ancestral sin corrupted their existence (their bodies and environment) that each person is born into and thus we are born into a corrupted existence (by the ancestral sin of [[Adam and Eve]]){{sfn|Rōmanidēs|Gabriel|2002|p=8}} and that "original sin is hereditary. It did not remain only Adam and Eve's. As life passes from them to all of their descendants, so does original sin. All of us participate in original sin because we are all descended from the same forefather, Adam."<ref>Metropolitan Archbishop Sotirios. [https://web.archive.org/web/20110726122920/http://www.gocanada.org/catechism/catorsin.htm "Original Sin And Its Consequences"]. ''Orthodox Catechism: Basic Teachings of the Orthodox Faith''</ref> The teaching of the Eastern Orthodox Church is that, as a result of Adam's sin, "hereditary sin flowed to his posterity; so that everyone who is born after the flesh bears this burden, and experiences the fruits of it in this present world."{{sfn|Bratcher|2018}}

Similarly, what the Catholic Church holds is that the sin of Adam that we inherit, and for the remission of which even babies who have no personal sin are baptized,{{sfn|Catholic Church|1994|p=102|loc=para 403}} is called "sin" only in an analogical sense since it is not an act committed like the personal sin of Adam and Eve, but a fallen state contracted by the transmission of a human nature deprived of original holiness and justice.{{sfn|Catholic Church|1994|p=102|loc=para 405}}

Both East{{Citation needed|date=June 2010}} and West{{sfn|Catholic Church|1994|p=102|loc=para 405}} hold that each person is not called to atone for the actual sin committed by Adam and Eve. <!-- (The following is not about original sin: Rather each person is called to overcome the corrupted world they are born into and seek salvation by way of the community established by God. By attaining the Holy Spirit which validates this community (church).<ref>[https://www.vatican.va/archive/ENG0015/__P28.HTM Catechism of the Catholic Church, 797–798]. Vatican.va. Retrieved 2 June 2012.</ref> Here the two churches greatly differ, as to the meaning of attaining the Holy Spirit, both having radically different meanings East and West.<ref>A Comparison: Francis of Assisi and St. Seraphim of Sarov by Father George Macris [http://www.orthodoxinfo.com/praxis/francis_sarov.aspx]</ref><ref>From Saint [[Seraphim of Sarov]] On Acquisition of the Holy Spirit by [[Nikolay Motovilov]] [http://www.greekorthodoxchurch.org/saint_seraphim.html]</ref> -->

According to the Western Church, "original sin does not have the character of a personal fault in any of Adam's descendants",{{sfn|Catholic Church|1994|p=102|loc=para 405}} and the Eastern Church teaches that "by these fruits and this burden we do not understand [actual] sin".{{sfn|Bratcher|2018}} The Orthodox{{Citation needed|date=June 2010}} and the Catholics{{sfn|Catholic Church|1994|p=105|loc=para 418}} believe that people inherit only the spiritual sickness (in which all suffer and sin) of Adam and Eve, caused by their ancestral sin (what has flowed to them), a sickness leaving them weakened in their powers, subject to ignorance, suffering from the domination of death, and inclined to sin.{{sfn|Catholic Church|1994|p=105|loc=para 418}}

=====Immaculate Conception=====
The Catholic doctrine of the [[Immaculate Conception]], which claims that God protected the [[Virgin Mary]] from original sin through no merit of her own,{{sfn|Trigilio|Brighenti|2011}}{{sfn|Macquarrie|2001|p=75}} was dogmatically defined by Pope [[Pius IX]] in 1854. Orthodox theology proclaims that Mary was chosen to bear Christ, having first found favor of God by her purity and obedience.{{sfn|Ware|1995|p=77}}{{sfn|Azkoul|1994}}<ref name="theotokos" /><ref name="encyc_1895" />{{sfn|Sparks|2008|p=1363}}<ref>{{bibleverse|Luke|1:30–31|NKJV}}</ref>

====Sin, purgatory, and hell====

=====Purgatory=====
Another point of theological contention between the western and eastern churches is the doctrine of [[purgatory]] (as it was shown at the [[Second Council of Lyon]] and the Council of Ferrara–Florence).{{sfn|Rausch|Clifford|2003|p=20}} It was developed in time in Western theology, according to which "all who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of heaven."{{sfn|Catholic Church|1994|p=268|loc=para 1030}} However, some Eastern theologians, while agreeing that there is beyond death a state in which believers continue to be perfected and led to full divinization, consider that it is a state not of punishment but of growth.{{sfn|Campbell|1996|p=54}} They hold that suffering cannot purify sin, since they have a different view of sin and consider suffering as a result of a spiritual sickness.{{sfn|Azkoul|1994}} Western theology usually considers sin not only as a sickness that weakens and impedes but also as something that merits punishment.{{sfn|Catholic Church|1994|p=456|loc=para 1863}}

The Eastern Orthodox Church holds that "there is a state beyond death where believers continue to be perfected and led to full divinization".{{sfn|Campbell|1996|p=54}}{{Citation needed|reason=please find an orthodox source|date=June 2010}} Although some Orthodox{{Who|date=June 2010}} have described this intermediate state as ''purgatory'', others distinguish it from aspects associated with it in the West: at the Council of Ferrara–Florence, the Orthodox Bishop [[Mark of Ephesus]] argued that there are in it no purifying fires.{{sfn|Vlachos|1996|loc=[https://web.archive.org/web/20090219210756/http://www.pelagia.org/htm/b24.en.life_after_death.05.htm#pu2 2. "The teaching of St. Mark Eugenicus about the purifying fire"]}}

Some Orthodox Christians also subscribe to the belief of [[aerial toll house]]s, which states that souls are tested by demons while on their way to Heaven. This concept is not found in Roman Catholicism.

=====Damnation=====
The traditional Orthodox teaching is that those who reject Christ will suffer his absence. According to the Confession of [[Dositheos II of Jerusalem|Dositheus]], "persons go immediately to joy in Christ or to the torments of punishment".{{sfn|Campbell|1996|p=54}} In Orthodox doctrine, there is no place without God. In eternity there is no hiding from God. In Catholic theology, God is present everywhere not only by his power but in himself.{{sfn|Toner|1913}} Hell is a state of self-selected separation from God.

Eastern theology considers the desire to sin to be the result of a spiritual sickness (caused by Adam and Eve's pride), which needs to be cured.<ref name="OrthodoxCatechism#24" /> One such theologian gives his interpretation of Western theology as follows: "According to the holy Fathers of the Church, there is not an uncreated Paradise and a created Hell, as the Franco–Latin tradition teaches".{{sfn|Vlachos|1996|loc=[https://web.archive.org/web/20111227233654/http://www.pelagia.org/htm/b24.en.life_after_death.07.htm Ch.7 Paradise and Hell]}} The Eastern Church believes that hell and heaven exist with reference to being with God, and that the very same divine love (God's uncreated energies) which is a source of bliss and consolation for the righteous (because they love God, His love is heaven for them) is also a source of torment (or a "Lake of Fire") for sinners.<ref name="OrthodoxCatechism#53" /><ref name="Romanides_Filioque" />{{sfn|Vlachos|1996|loc=[https://web.archive.org/web/20111227233654/http://www.pelagia.org/htm/b24.en.life_after_death.07.htm Ch.7 "Paradise and Hell"]}}{{sfn|Lossky|1976|p=234}} The Western Church speaks of heaven{{sfn|Catholic Church|1994|p=267|loc=para 1024}} and hell{{sfn|Catholic Church|1994|p=269|loc=para 1033}} as states of existence rather than as places, while in Eastern Orthodoxy there is no hell per se, there is a "hell" in the absence of God's grace. To quote St John of Damascus: "God does not punish but each one decides on his receiving of God, whose reception is joy and his absence a hell (Gr. {{lang|grc|κόλασις}})".{{CN|date=February 2023}}

=== Governance ===
The [[Byzantine Empire]] was a [[theocracy]]; the emperor was the supreme authority in both church and state.{{sfn|Herrin|2013|p=11}}{{sfn|VanVoorst|2012|p=14}}{{sfn|Stefoff|2008|p=62}}{{sfn|Dawson|2008|p=140}} "The king is not God among men but the Viceroy of God. He is not the {{lang|grc-Latn|logos}} incarnate but is in a special relation with the {{lang|grc-Latn|logos}}. He has been specially appointed and is continually inspired by God, the friend of God, the interpreter of the Word of God. His eyes look upward, to receive the messages of God. He must be surrounded with the reverence and glory that befits God's earthly copy; and he will 'frame his earthly government according to the pattern of the divine original, finding strength in its conformity with the monarchy of God{{'"}}.{{sfn|Schaff|1904}}{{sfn|Runciman|2004}}

In the East, endorsement of [[caesaropapism]], the subordination of the church to the religious claims of the dominant political order, was most fully evident in the Byzantine Empire at the end of the first millennium,<ref name="encarta1" /> while in the West, where the decline of imperial authority left the Church relatively independent,<ref name="encarta2" />{{sfn|Dwyer|1998|p=118}}{{sfn|Bunson|2014|p=115}}{{sfn|Geanakoplos|1989|p=226}} there was a growth in the power of the papacy. As a result of the [[Early Muslim conquests|Muslim conquests]] of the territories of the patriarchates of Alexandria, Antioch and Jerusalem, only two rival powerful centres of ecclesiastical authority, Constantinople and Rome, remained.{{sfn|Knowles|Cunningham|2019}} Until this happened, Rome often tried to act as a neutral mediator in disputes among the Eastern patriarchates.

In Eastern [[Christendom]], the teaching of papal supremacy is said to be based on the [[pseudo-Isidorian Decretals]],{{sfn|Krehel|2017}} documents attributed to early popes but actually forged, probably in the second quarter of the 9th century, with the aim of defending the position of bishops against metropolitans and secular authorities. The Orthodox East contests the teaching that Peter was the [[Patriarch of Rome]], a title that the West too does not give him. Early sources such as St. [[Irenaeus]] can be interpreted as describing [[Pope Linus]] as the first bishop of Rome and [[Pope Cletus]] the second.{{sfn|Kelly|Walsh|2005|p=6}}

The ''Oxford Dictionary of Popes'' states: "In the late 2nd or early 3rd cent. the tradition identified Peter as the first bishop of Rome. This was a natural development once the monarchical episcopate, i.e. the government of the local church by a single bishop, as distinct from a group of presbyter-bishops, finally emerged in Rome in the mid-2nd cent. The earlier tradition, however, which placed Peter and Paul in a class apart as the pioneers who together established the Roman church and its ministry, was never lost sight of."{{sfn|Kelly|Walsh|2005|p=6}}

St. Peter was according to tradition [[bishop of Antioch]] at one point, and was then succeeded by [[Saint Evodius|Evodius]] and [[Ignatius of Antioch|Ignatius]]. The Eastern Orthodox do not hold the primacy of the Pope of Rome over the Eastern church; they teach that the Pope of Rome is the first among equals. The [[first seven Ecumenical Councils]] were held in the East and called by the Eastern Emperors; the Roman pontiff never presided over any of them.{{efn|The Orthodox attitude to the papacy is expressed by a 12th-century writer, [[Nicetas of Nicomedia|Nicetas]], Archbishop of Nicomedia:
{{Blockquote|My dearest brother, we do not deny to the Roman Church the primacy amongst the five sister Patriarchates; and we recognize her right to the most honorable seat at an Ecumenical Council. But she has separated herself from us by her own deeds, when through pride she assumed a monarchy which does not belong to her office&nbsp;... How shall we accept decrees from her that have been issued without consulting us and even without our knowledge? If the Roman Pontiff, seated on the lofty throne of his glory, wishes to thunder at us and, so to speak, hurl his mandates at us from on high, and if he wishes to judge us and even to rule us and our Churches, not by taking counsel with us but at his own arbitrary pleasure, what kind of brotherhood, or even what kind of parenthood can this be? We should be the slaves, not the sons, of such a Church, and the Roman See would not be the pious mother of sons but a hard and imperious mistress of slaves|source=<ref>{{harvnb|Runciman|1955|p= 116}} and {{harvnb|Ware|1963}}</ref> }}
}}

==History==
{{Main|History of the East–West Schism}}
{{See also|History of Christianity}}
<!---please do not add material here that is not first in "History of the East–West Schism". The material here is a summary of that article. Also, material inserted here now, that is not first inserted into "History of East–West Schism" might be inadvertently compressed out here and not in History section either!--->{{summarize|from|History of the East–West Schism|section=y|brevity=y|date=August 2016}}

The schism between the Western and Eastern Mediterranean Christians resulted from a variety of political, cultural and theological factors which transpired over centuries.{{sfn|Phan|2000|p=37}} Historians regard the mutual excommunications of 1054 as the terminal event.{{sfn|Haight|2004|p=289}} It is difficult to agree on a date for the event where the start of the schism was apparent.{{sfn|Becchio|Schadé|2006|p=805}} It may have started as early as the{{citation needed|date=February 2020}}<!---footnote originally intended to identify scholars who argued this--> [[Quartodeciman]] controversy at the time of [[Pope Victor I|Victor of Rome]] (c. 180). Orthodox apologists point to this incident as an example of claims by Rome to the papal primacy and its rejection by Eastern Churches.

Sporadic schisms in the common unions took place under [[Pope Damasus I]] in the 4th and 5th centuries.{{sfn|Soloviev|2009|p=14}}{{sfn|Makrides|2009|p=68}}{{sfn|Nichols|2010|pp=227–272}} Disputes about theological and other questions led to schisms between the Churches in Rome and Constantinople for 37 years from 482 to 519 (the [[Acacian Schism]]). Most sources agree that the separation between East and West is clearly evident by the [[Photian schism]] in 863 to 867.

===Claims of the See of Rome===
While the church at Rome claimed a special authority over the other churches, the extant documents of that era yield "no clear-cut claims to, or recognition, of papal primacy."{{sfn|Kling|2004|p=61}}{{sfn|Hopko|2005}}

Towards the end of the 2nd century, Victor, the Bishop of Rome, attempted to resolve the Quartodeciman controversy. The question was whether to celebrate Easter concurrently with the Jewish [[Passover]], as Christians in the Roman province of Asia did, or to wait until the following Sunday, as was decreed by synods held in other Eastern provinces, such as those of [[Roman province of Palestine|Palestine]] and [[Diocese of Pontus|Pontus]], the acts of which were still extant at the time of [[Eusebius]], and in Rome.{{sfn|Schaff|1904|p=241|loc=Ch. XXIII}}<ref name="OrthAns">{{Cite web |url=http://www.orthodoxanswers.org/history |title=An Orthodox Christian Historical Timeline |publisher=Orthodox Answers |url-status=dead |archive-url=https://web.archive.org/web/20120723192152/http://www.orthodoxanswers.org/history |archive-date=23 July 2012 |access-date=23 February 2013}}</ref> The pope attempted to excommunicate the churches in Asia, which refused to accept the observance on Sunday. Other bishops rebuked him for doing so.{{sfn|Schaff|1904|p=242|loc=Ch. XXIV}} Laurent Cleenewerck comments:

{{Blockquote|Victor obviously claimed superior authority, probably from St. Peter, and decided – or at least "attempted" to excommunicate a whole group of Churches because they followed a different tradition and refused to conform. One could therefore argue that the Great schism started with Victor, continued with Stephen and remained underground until the ninth century! But the question is this: even if Victor was not acting wisely, did he not have the power to "cut off whole Churches"? This is what Roman Catholics argue with the implication that such an excommunication would be ontologically meaningful and put someone "outside the Catholic Church". Yet, we do not see bishops "pleading" but indeed "sharply rebuking" and "admonishing" Victor. Ultimately this is why his letters of excommunication came to no effect. Nevertheless it is possible to read in Eusebius' account the possibility that St. Irenaeus recognized that Victor could indeed "cut off whole Churches" and that such excommunication would have been ontologically meaningful. ... In the end, it took some patience and [[First Council of Nicaea|an Ecumenical Council]] to achieve what Victor could not achieve by his threat to excommunicate.{{sfn|Cleenewerck|2007|p=156}} }}

Despite Victor's failure to carry out his intent to excommunicate the Asian churches, a number of Catholic apologists point to this episode as evidence of papal primacy and authority in the early Church, citing the fact that none of the bishops challenged his right to excommunicate but instead questioned the wisdom and charity of his action.{{sfn|Cleenewerck|2007|p=156}} Anglican apologists question the premise that Victor even asserted what he imagined to be supremacy:

{{Blockquote| Victor’s action is inexplicable on the hypothesis that the Papal Monarchy is jure divino. If that were so, he must have adopted, in discharge of his duty as Supreme Shepherd, a very different course. He, the Supreme judge, having 'supreme jurisdiction' which is 'immediate,' 'ordinary,' and 'truly Episcopal,' over the Asiatic churches, would have commanded them by his 'real and sovereign authority, which the whole community is bound to obey'—which could receive no increase of authority from Synods—to conform their usage to his judgment, which could not be reviewed. A man, too, of his temperament would certainly not fail to use to the uttermost whatever authority he possessed. His action shows that, however harshly he may in his intolerance have pressed the matter, he evidently had no idea that any such 'sovereign' power was possessed by him.{{CN|date=February 2023}} }}

The opinion of the bishop of Rome was often sought, especially when the patriarchs of the Eastern Mediterranean were locked in fractious dispute. However, the bishop of Rome's opinion was by no means accepted automatically. The bishops of Rome never obviously belonged to either the [[School of Antioch|Antiochian]] or the [[Catechetical School of Alexandria|Alexandrian]] schools of theology, and usually managed to steer a middle course between whatever extremes were being propounded by theologians of either school. Because Rome was remote from the centers of Christianity in the eastern Mediterranean, it was frequently hoped its bishop would be more impartial. For instance, in 431, [[Cyril of Alexandria|Cyril]], the patriarch of Alexandria, appealed to [[Pope Celestine I]], as well as the other patriarchs, charging Constantinople Patriarch [[Nestorius]] with heresy, which was dealt with at the [[First Council of Ephesus|Council of Ephesus]]. He nevertheless believed Rome's capacity to excommunicate Nestorius to only be effective in the West.{{CN|date=February 2023}}

In 342, [[Pope Julius I]] wrote: "The custom has been for word to be written first to us [in the case of bishops under accusation, and notably in apostolic churches], and then for a just sentence to be passed from this place".{{sfn|Nichols|2010|p=199}} This was also decreed by the [[Council of Sardica]], which declared Saint [[Athanasius]] to be the lawful bishop of Alexandria.{{sfn|Schaff|1916|pp=413–414|loc=Ch. IX Council of Sardica}}

In [[Council of Rome|382 a synod in Rome]] protested against the raising of Constantinople to a position above that of Alexandria and spoke of Rome as "the [[apostolic see]]".{{sfn|Nichols|2010|p=202}} [[Pope Siricius]] (384–399) claimed for papal decretals the same binding force as decisions of synods, [[Pope Innocent I]] (401–417) said that all major judicial cases should be reserved for the see of Rome, and [[Pope Boniface I]] (418–422) declared that the church of Rome stands to "the churches throughout the world as the head to its members" and that bishops everywhere, while holding the one same episcopal office, must "recognise those to whom, for the sake of ecclesiastical discipline, they should be subject".{{sfn|Nichols|2010|p=203}}

Celestine I ({{Reign|422|432|lk=abbr}}) considered that the condemnation of Nestorius by his own Roman synod in 430 was sufficient, but consented to the general council as "of benefit in manifesting the faith".{{efn| The [[First Council of Ephesus]] in 431 stated that it condemned Nestorius "compelled thereto by the canons and by the letter of our most holy father and fellow-servant [[Pope Celestine I|Coelestine]], the Roman bishop"{{sfn|Schaff|1916|p=178|loc=Ch. III The First Council of Constantinople, Canon III}}{{sfn|Nichols|2010|p=203}} }} [[Pope Leo I]] and his successors rejected canon 28 of the [[Council of Chalcedon]], as a result of which it was not officially recorded even in the East until the 6th century.{{sfn|Michalopulos|2009}}{{sfn|Nichols|2010|p=208}} The Acacian schism, when, "for the first time, West lines up against East in a clear-cut fashion",{{sfn|Nichols|2010|pp=209–210}} ended with acceptance of a declaration insisted on by [[Pope Hormisdas]] (514–523) that "I hope I shall remain in communion with the apostolic see in which is found the whole, true, and perfect stability of the Christian religion".{{sfn|Nichols|2010|p=210}}{{sfn|Whitehead|2000|pp=244–}}{{sfn|Ayer|1941|p=537}} Yet, "the vast majority of the Eastern Bishops subscribed quite a different Formula."{{CN|date=February 2023}}

Earlier, in 494, [[Pope Gelasius I]] (492–496) wrote to Byzantine emperor, [[Anastasius I (emperor)|Anastasius]], distinguishing the power of civil rulers from that of the bishops (called "priests" in the document), with the latter supreme in religious matters; he ended his letter with: "And if it is fitting that the hearts of the faithful should submit to all priests in general who properly administer divine affairs, how much the more is obedience due to the bishop of that see which the Most High ordained to be above all others, and which is consequently dutifully honoured by the devotion of the whole Church."{{sfn|Robinson|1905|pp=72–73}} [[Pope Nicholas I]] (858–867) made it clear that he believed the power of the papacy extended "over all the earth, that is, over every church".{{sfn|Ware|1963|p=51}}{{sfn|Galli|1997}}

===Claims of the See of Constantinople===
[[File:Santa Sofía.jpg|thumb|[[Hagia Sophia]], the cathedral of Constantinople at the time of the schism]]

In 330, [[Roman Emperor|Emperor]] [[Constantine I|Constantine]] moved the imperial capital to [[Byzantium]], which later became [[Constantinople]].{{sfn|Rautman|2006|p=17}} The centre of gravity in the empire was fully recognised to have completely shifted to the [[eastern Mediterranean]]. Rome lost the [[Roman Senate|Senate]] to Constantinople and lost its status and gravitas as imperial capital.{{efn|See also the [[Fall of Rome]]}}

The bishop of [[Byzantium]] was under the authority of the [[metropolitan archbishop|metropolitan]] of [[Perinthus|Heraclea]] when Constantine moved there.{{sfn|Ware|1963}} Thereafter, the bishop's connection with the imperial court meant that he was able to free himself from ecclesiastical dependency on Heraclea and in little more than half a century to obtain recognition of next-after-Rome ranking from the [[First Council of Constantinople]] (381), held in the new capital. It decreed: "The Bishop of Constantinople, however, shall have the prerogative of honour after the Bishop of Rome; because Constantinople is New Rome",{{sfn|Schaff|1916|p=178|loc=Ch. III The First Council of Constantinople, Canon III}} thus raising it above the sees of Alexandria and Antioch. This has been described as sowing the seed for the ecclesiastical rivalry between Constantinople and Rome that was a factor leading to the schism between East and West.{{sfn|Geanakoplos|1989|p=172}}{{sfn|Baker|Landers|2005|p=110}} The website of the Orthodox Church in America says that the Bishop of Byzantium was elevated to [[Patriarch]] already in the time of Constantine.<ref name="oca.org" />

Disunion in the Roman Empire contributed to disunion in the Church. [[Theodosius I|Theodosius the Great]], who in 380 established [[First Council of Nicaea|Nicene]] Christianity as the [[state church of the Roman Empire|official religion of the Roman Empire]] (see [[Edict of Thessalonica]]), was the last Emperor to rule over a united Roman Empire. Following the death of Theodosius in 395, the Empire was divided for the final time into western and eastern halves. In the [[Christianity in the 4th century|4th century]], the Roman emperor (reigning in Constantinople) started to control the Church in his territory.{{sfn|Binns|2002|pp=162–164}}

The patriarchs of Constantinople often tried to adopt a commanding position over the other patriarchs, provoking their resistance. For example, in 431 Patriarch Cyril of Alexandria impeached for heresy Patriarch Nestorius of Constantinople.{{sfn|McGuckin|1994|p=173}}

Alexandria's objections to Constantinople's promotion, which led to a constant struggle between the two sees in the first half of the 5th century,{{sfn|Schatz|1990|loc=Part II}} were supported by Rome, which proposed the theory that the most important sees were the three Petrine ones, of Rome, Antioch, and Alexandria,{{sfn|Gaillardetz|Wilson|2003|p=211}} with Rome in the first place.

However, the power of the patriarch of Constantinople continued to grow.<ref name="patriarchate.org" /> Eastern Orthodox state that the 28th canon of the Council of Chalcedon (451){{sfn|Schaff|1916|p=287|loc=Ch. V. The Council of Chalcedon, Canon XXVIII}} explicitly proclaimed the equality of the Bishops of Rome and Constantinople, and that it established the highest court of ecclesiastical appeal in Constantinople.{{sfn|Schaff|1916|p=287|loc=Ch. V. The Council of Chalcedon, Canon XXVIII}} The patriarch of the imperial capital succeeded in his efforts{{sfn|Bunson|2014|p=115}} to become the leading bishop in the Byzantine Empire: he "headed a vast curia and other bishops who resided in Constantinople constituted [[Endemic synod|a permanent synod]], which became the real governing body of the [[state church of the Roman Empire|church]]".{{sfn|Becchio|Schadé|2006|loc=§8}}

Patriarch [[John IV of Constantinople]], who died in 595, assumed the title of "Ecumenical Patriarch".{{sfn|Michalopulos|2009}}

The idea that with the transfer of the imperial capital from Rome to Constantinople, primacy in the Church was also transferred, is found in undeveloped form as early as [[John Philoponus]] (c. 490 – c. 570). It was enunciated in its most advanced form by [[Photios I of Constantinople]] (c. 810 – c. 893). Constantinople, as the seat of the ruler of the empire and therefore of the world, was the highest among the patriarchates and, like the emperor, had the right to govern them.{{sfn|Anastos|2001}}

===Council of Nicaea (325)===
{{main|First Council of Nicaea}}
{{See also|Constantine the Great and Christianity|Byzantinism}}
[[File:Nicaea icon.jpg|thumb|Icon depicting [[Constantine I|the Emperor Constantine]] (centre) and the [[bishop]]s of the [[First Council of Nicaea]] (325) holding the [[Niceno-Constantinopolitan Creed|Niceno–Constantinopolitan Creed of 381]]]]

After the Roman Emperor [[Constantine the Great]] legalized Christianity (with the [[Edict of Milan]]), he summoned the [[First Ecumenical Council]] at [[Nicaea]] in 325. The bishops at the council confirmed the position of the [[metropolitan see]]s of Rome and Alexandria as having authority outside their own province, and also the existing privileges of the churches in Antioch and the other provinces.{{sfn|Schaff|1916|p=15|loc=Ch. I: The First Council of Nice}} These sees were later called [[Patriarchate]]s.{{Citation needed|date=May 2010}} These were given an [[order of precedence]]: Rome, as the capital of the empire, was naturally given first place, then came Alexandria and Antioch. In a separate canon the Council also approved the special honor given to [[Jerusalem in Christianity|Jerusalem]] over other sees subject to the same metropolitan.{{sfn|Schaff|1916|p=17|loc=The First Council of Nice, Canon VII}}

===First Council of Constantinople (381)===
{{Further|Patriarchate}}
[[Dominate|Roman dominate]] [[Roman Emperor (Dominate)|Emperor]] [[Theodosius I]] convened the [[second ecumenical council]] (Constantinople I) at the imperial capital city in 381. The council elevated the see of Constantinople to a position ahead of the other chief metropolitan sees, except that of Rome, thus raising it above the sees of Alexandria and Antioch.{{efn|Following the establishment of Constantinople (the ancient city of Byzantium) as the state capital of the Roman Empire in the early part of the 4th century, a series of significant ecclesiastical events saw the status of the Bishop of [[New Rome]] (as Constantinople was then called) elevated to its current position and privilege.<ref name="patriarchate.org" />}} This action has been described as sowing the seed for the ecclesiastical rivalry between Constantinople and Rome which was ultimately a factor leading to the schism between East and West.{{sfn|Geanakoplos|1989|p=172}}{{sfn|Baker|Landers|2005|p=110}}{{sfn|Schaff|1916|p=178|loc=Ch. III The First Council of Constantinople, Canon III}}

{{citation needed span|text=It demarcated the territory within the [[praetorian prefecture of the East]] into five canonical territories corresponding to the five [[civil diocese]]s: [[Diocese of Egypt]] ([[Metropolis (religious jurisdiction)|metropolis]] in Alexandria), [[Diocese of the East]] (metropolis in Antioch), [[Diocese of Asia]] ([[Metropolis of Ephesus]]), Diocese of Pontus (metropolis in [[Caesarea Cappadociae]]), and [[Diocese of Thrace]] (metropolis in [[Perinthus|Heraclea]], later under Constantinople);|date=June 2016|reason=Constantinople I canon 2 does mention these places but is not explicit that demarcation was done by this council. A secondary source should explain.}}{{sfn|Schaff|1916|pp=176–177|loc=Ch. III The First Council of Constantinople, Canon II}} The council mentioned the churches in the civil dioceses of Asia, Pontus, and Thrace, decreeing that the synod of each province should manage the ecclesiastical affairs of that province alone, except for the privileges already recognized for the sees of Alexandria and Antioch.{{sfn|Schaff|1916|pp=176–177|loc=Ch. III The First Council of Constantinople, Canon II}}

Generally, no Western bishops attended the council,{{sfn|Collier|1911}} though [[Ascholius]] of Thessalonica (a city under Roman jurisdiction at that time) did attend and was tasked by Pope Damasus to "insure that an utterly blameless bishop" be elected for Constantinople.{{CN|date=February 2023}} The Latin Church appears to have initially accepted the canons of this council as evidenced to one of them being cited by a Roman legate during the [[Council of Chalcedon]]{{CN|date=February 2023}} and all extant sources include these canons.<ref>https://biblehub.com/library/schaff/the_seven_ecumenical_councils/introduction_on_the_number_of.htm Hefele, History of the Councils, Vol. II., p.351.</ref>

===Chalcedon (451)===
Rome's [[Tome of Leo]] (449) was highly regarded and formed the basis for the Council of Chalcedon formulation. But it was not universally accepted and was even called "impious" and "blasphemous" by those who condemned the council that approved and accepted it.{{sfn|Severus|1903|p=254}} The next ecumenical council corrected a possible imbalance in Pope Leo's presentation. Although the Bishop of Rome was well respected even at this early date, the East holds that the concept of the primacy of the Roman See and [[Papal Infallibility]] were only developed much later.

The disputed{{sfn|Michalopulos|2009}}<ref name="orthodoxytoday.org2005.02.01" /> canon 28 of the Council of Chalcedon in 451, confirming the authority already held by Constantinople, granted its archbishop jurisdiction over Pontus and Thrace.{{sfn|Schaff|1916|p=287|loc=Ch. V. The Council of Chalcedon, Canon XXVIII}}

The council also ratified an agreement between Antioch and Jerusalem, whereby Jerusalem held jurisdiction over three provinces,{{sfn|Schaff|1916|p=266|loc=Ch. V. The Council of Chalcedon, Decree on the Jurisdiction of Jerusalem and Antioch}} numbering it among the [[Pentarchy|five great sees]].{{sfn|Ware|1963|p=34}} As thus interpreted, there were now five patriarchs presiding over the Church within the [[Byzantine Empire]], in the following order of precedence: the [[Patriarch of Rome]], the [[Ecumenical Patriarch of Constantinople|Patriarch of Constantinople]], the [[Patriarch of Alexandria]], the [[Patriarch of Antioch]] and the [[Greek Orthodox Patriarch of Jerusalem|Patriarch of Jerusalem]].

Although Leo I, whose delegates were absent when this resolution was passed, recognized the council as ecumenical and confirmed its doctrinal decrees, he rejected its canon 28 on the ground that it contravened the sixth canon of Nicaea and infringed the rights of Alexandria and Antioch.{{sfn|Collier|1911}}

This canon would remain a constant source of friction between East and West until the mutual excommunications of 1054 made it irrelevant in that regard;{{sfn|McGuckin|2010|pp=32, 137}} but controversy about its applicability to the authority of the patriarchate of Constantinople still continues.{{sfn|McGuckin|2010|p=137}}

The same disputed canon also recognized the authority of Constantinople over bishops of dioceses "among the barbarians", which has been variously interpreted as referring either to all areas outside the Byzantine Empire or only to those in the vicinity of Pontus, Asia and Thrace or to non-Greeks within the empire.{{sfn|Michalopulos|2009}}

Canon 9 of the Council also declared: "If a bishop or clergyman should have a difference with the metropolitan of the province, let him have recourse to the Exarch of the Diocese, or to the throne of the Imperial City of Constantinople, and there let it be tried." This has been interpreted as conferring on the see of Constantinople a greater privilege than what any council ever gave Rome, or as of much lesser significance than that.{{sfn|Schaff|1916|p=274|loc=Ch. V. The Council of Chalcedon, Canon IX, Notes}}

===Separation of the West from the Roman Empire===
{{See also|Fall of the Western Roman Empire}}
In 476, when the last emperor of the western part of the [[Roman Empire]] was [[Deposition of Romulus Augustulus|deposed]] and the western imperial insignia were sent to Constantinople, there was once again a single Roman Emperor. However, he had little power in the West, which was ruled almost entirely by various Germanic tribes. In the opinion of Randall R. Cloud, the permanent separation of the Greek East from the Latin West was "the fundamental reason for the estrangement that soon followed between the Greek and the Latin Christians".{{sfn|Cloud|2009|p=222}}

The dominant language of the West was [[Latin]], while that of the East was [[Greek language|Greek]]. Soon after the fall of the West to invaders, the number of individuals who spoke both languages dwindled, and communication between East and West grew much more difficult. With linguistic unity gone, cultural unity began to crumble as well. The two halves of the Church were naturally divided along similar lines; they developed different [[Christian liturgy|rite]]s and had different approaches to religious doctrines. Although the schism was still centuries away, its outlines were already perceptible.<ref name="orthodox.org.ph" />

In the areas under his control, [[Justinian I]] established [[caesaropapism]] as the constitution of the Church in a scheme according to which the emperor "had the right and duty of regulating by his laws the minutest detail of worship and discipline, and also of dictating the theological opinions to be held in the Church".{{sfn|Ayer|1941|p=325}} According to the ''Westminster Dictionary of Theological Terms'', this caesaropapism was "a source of contention between Rome and Constantinople that led to the schism of 1054".{{sfn|McKim|1996|p=35}} Explicit approval of the emperor in Constantinople was required for consecration of bishops within the empire. During the period called the [[Byzantine Papacy]], this applied to the bishops of Rome, most of whom were of Greek or Syrian origin. Resentment in the West against the Byzantine emperor's governance of the Church is shown as far back as the 6th century, when "the tolerance of the [[Theoderic the Great|Arian Gothic king]] was preferred to the caesaropapist claims of Constantinople".{{sfn|Wolfram|1990|p=328}} The origins of the distinct attitudes in West and East are sometimes traced back even to [[Augustine of Hippo]], who "saw the relationship between church and state as one of tension between the 'city of God' and the 'city of the world{{'"}}, and [[Eusebius]], who "saw the state as the protector of the church and the emperor as God's vicar on earth".{{sfn|Volz|2011|p=73}}

===Decline of three patriarchates===
By 661, Muslim Arabs had [[Early Muslim conquests|taken over]] the territories assigned to the patriarchates of Alexandria, Antioch and Jerusalem, which thereafter were never more than partially and temporarily recovered. In 732, Emperor [[Leo III the Isaurian]], in revenge for the opposition of [[Pope Gregory III]] to the emperor's [[iconoclasm (Byzantine)|iconoclast]] policies, transferred Sicily, Calabria and Illyria from the patriarchate of Rome (whose jurisdiction until then extended as far east as Thessalonica) to that of Constantinople.{{sfn|Kaegi|2019}} The Constantinople Patriarchate, after expanding eastward at the time of the Council of Chalcedon to take in Pontus and the Roman province of Asia, which at that time were still under the emperor's control, thus expanded equally to the west and was practically coextensive with the Byzantine Empire.

===Council in Trullo (Quinisext, 692)===
The West's rejection of the [[Quinisext Council]] of 692 led to pressure from the Eastern Empire on the West to reject multiple Latin customs as non-Orthodox. The Latin practices that had got the attention of the other Patriarchates{{Citation needed|date=November 2012}} and that had been condemned by this Council included the practice of celebrating [[Mass (liturgy)|Mass]] on weekdays in [[Great Lent|Lent]] (rather than having [[Divine Liturgy of the Presanctified Gifts|Pre-Sanctified Liturgies]]);{{sfn|Schaff|1916|p=391|loc=Ch. VIII The Canons of the Council in Trullo, Canon LII}} [[fasting]] on Saturdays throughout the year;{{sfn|Schaff|1916|p=389|loc=Ch. VIII The Canons of the Council in Trullo, Canon LV}} omitting the "[[Alleluia]]" in Lent; depicting Christ as a [[Lamb of God|lamb]];{{sfn|Schaff|1916|p=401|loc=Ch. VIII The Canons of the Council in Trullo, Canon LXXXII}} using unleavened bread.{{sfn|Schaff|1916|p=370|loc=Ch. VIII The Canons of the Council in Trullo, Canon XI}}

Larger disputes were revealed regarding Eastern and Western attitudes toward [[clerical celibacy|celibacy]] for priests and [[deacon]]s, with the Council affirming the right of married men to become priests (though forbidding priests to marry and forbidding bishops to live with their wives){{sfn|Schaff|1916|p=364|loc=Ch. VIII The Canons of the Council in Trullo, Canon VI}}{{sfn|Schaff|1916|p=370|loc=Ch. VIII The Canons of the Council in Trullo, Canon XII}} and prescribing deposition for anyone who attempted to separate a clergyman other than a bishop from his wife, or for any cleric other than a bishop who dismissed his wife.{{sfn|Schaff|1916|p=371|loc=Ch. VIII The Canons of the Council in Trullo, Canon XIII}}

[[Pope Sergius I]], who was of Syrian ancestry, rejected the council.{{sfn|Ekonomou|2007|p=222}} Emperor [[Justinian II]] ordered his arrest,{{sfn|Ekonomou|2007|p=223}} but this was thwarted.{{sfn|Ekonomou|2007|p=224}}{{sfn|Ullmann|2004|p=64}}

In 694, in [[Visigothic]] [[Hispania|Spain]], the council was ratified by the [[Eighteenth Council of Toledo]] at the urging of the king, [[Wittiza]]. [[Fruela I of Asturias]] reversed the decision of Toledo sometime during his reign (757–768).{{citation needed|date=March 2020}}

===Papal supremacy and Pentarchy===
{{Further|Pentarchy}}
The primary causes of the schism were disputes over conflicting claims of jurisdiction, in particular over [[papal supremacy|papal authority]]—[[Pope Leo IX]] claimed he held authority over the four Eastern [[patriarch]]s—and over the insertion of the [[Filioque clause]] into the [[Nicene Creed]] by the Western patriarch in 1014.{{sfn|Papadakis|Meyendorff|1994|p=14}} Eastern Orthodox today state that Council of Chalcedon canon 28 explicitly proclaimed the equality of the Bishops of Rome and Constantinople and that it established the highest court of ecclesiastical appeal in Constantinople.{{sfn|Hartmann|Pennington|2012|p=63}} Council of Ephesus canon 7 declared:
{{Blockquote|It is unlawful for any man to bring forward, or to write, or to compose a different ({{lang|grc|ἑτέραν}}) Faith as a rival to that established by the holy Fathers assembled with the Holy Ghost in Nicæa. But those who shall dare to compose a different faith, or to introduce or offer it to persons desiring to turn to the acknowledgment of the truth, whether from Heathenism or from Judaism, or from any heresy whatsoever, shall be deposed, if they be bishops or clergymen; bishops from the episcopate and clergymen from the clergy; and if they be laymen, they shall be [[anathematized]]|source={{harvnb|Schaff|1916|p=197|loc=Ch. IV The Council of Ephesus, Session I Extracts from the Acts}} }}

Eastern Orthodox today state that this canon of the Council of Ephesus explicitly prohibited modification of the Nicene Creed drawn up by the [[First Council of Nicaea|first Ecumenical Council]] in 325, the wording of which, it is claimed, but not the substance, had been modified by the [[First Council of Constantinople|second Ecumenical Council]], making additions such as "who proceeds from the Father".

Eastern Orthodox argue that the First Council of Ephesus canon 7 explicitly prohibited modification of the Nicene Creed by any man (not by ecumenical church council) drawn up by the first Ecumenical Council in 325.{{sfn|Schaff|1916|p=161|loc=Ch. III The First Council of Constantinople}} In reality, the Council made no exception for an ecumenical council or any other body of bishops,{{sfn|Schaff|1916|p=231|loc=Ch. IV The Council of Ephesus, Canon VII}} and the Greeks participating in the [[Council of Florence]] emphatically denied that even an ecumenical council had the power to add anything to the creed.{{sfn|Schaff|1916|p=232|loc=Ch. IV The Council of Ephesus, Excursus on the words πίστιν ἑτέραν}}

The creed quoted in the Acts of the Council of Ephesus of 431 (the third ecumenical council) is that of the first ecumenical council without the modifications that the [[First Council of Constantinople|second ecumenical council]], held in Constantinople in 381, is understood to have made to it, such as the addition of "who proceeds from the Father".{{sfn|Schaff|1916|p=197|loc=Ch. IV The Council of Ephesus, Session I Extracts from the Acts}} Eastern Orthodox theologians state this change of the wording of the churches' original creed was done to address various teachings outside of the church—specifically, that of [[Macedonius I of Constantinople]], which the council claimed was a distortion of the church's teaching on the Holy Spirit. This was not a change of the orthodoxy of the churches' original creed.{{sfn|Pomazansky|1984|p=17|loc=[http://www.intratext.com/IXT/ENG0824/_P17.HTM The equality of honor and the Divinity of the Holy Spirit.]}}

Thus the word {{lang|grc|ἑτέραν}} in the seventh canon of the later Council of Ephesus is understood as meaning "different" or "contradictory" and not "another" in the sense of mere explanatory additions to the already existing creed.{{sfn|Schaff|1916|p=232|loc=Ch. IV The Council of Ephesus, Excursus on the words πίστιν ἑτέραν}} Some scholars hold that the additions attributed to the First Council of Constantinople were adopted only with the 451 [[Council of Chalcedon]], 20 years after that of Ephesus,{{sfn|Kelly|2006|p=296}}{{sfn|Leith|1982|p=31}} and even that the Council of Ephesus, in which Alexandrian influence was dominant, was by this canon excluding the Constantinopolitan Creed, which eventually annexed the name and fame of the creed adopted at Nicaea.{{sfn|Hussey|1967|p=177}}

===Filioque and primacy issues (867–879)===
{{Main |Council of Constantinople (867)|Fourth Council of Constantinople (Catholic)|Fourth Council of Constantinople (Eastern Orthodox)}}

Three councils were held, two by Constantinople, one by Rome.{{sfn|Wilhelm|1908}} Rome attempted to replace a seated Patriarch with one amenable to the [[Filioque]] dispute. The Orthodox responded by denouncing the replacement and excommunicating the pope convening the Roman council, denouncing the pope's attempt to control affairs outside the purview of Rome, and denouncing the addition of [[Filioque]] as a heresy. Each church recognizes its own council(s) as legitimate and does not recognize the other's council(s).{{sfn|Fortescue|1907|pp=147–148}}{{sfn|Louth|2007|p=171}}{{sfn|Tougher|1997|p=69}}{{sfn|Siecienski|2010|p=103}}{{sfn|Fortescue|1907|pp=147–148}}{{sfn|Vauchez|Lapidge|2000|p=1016}}

===Mutual excommunication of 1054===
[[File:Byzantine Empire animated.gif|thumb|450px|Changes in the extent of the Empire ruled from Constantinople.<br /> 476 End of the Western Empire; 550 Conquests of Justinian I; 717 Accession of Leo the Isaurian; 867 Accession of Basil I; 1025 Death of Basil II; 1095 Eve of the First Crusade; 1170 Under Manuel I; 1270 Under Michael VIII Palaiologos; 1400 Before the fall of Constantinople]]
In 1053 [[Leo of Ohrid]], at the instigation, according to [[J. B. Bury]], of Patriarch [[Michael Cerularius]] of Constantinople,{{sfn|Bury|1923|p=200}} wrote to Bishop John of Trani a letter, intended for all the [[Latin Church|Latin]] bishops, including the pope, in which he attacked Western practices such as using [[azymes|unleavened bread]] for the Eucharist, and fasting rules that differed from those in Constantinople, while Cerularius himself closed all Latin churches in Constantinople.

In response, Leo IX wrote the letter ''In terra pax'' of 2 September 1053,{{sfn|Migne|1882|pp=744–769}} addressed to Cerularius and Leo of Ohrid, in which he speaks at length of the privileges granted through Saint Peter to the see of Rome. In one of the 41 sections of his letter he also speaks of privileges granted by the emperors, quoting from the ''[[Donation of Constantine]]'' document, which he believed to be genuine (section 20).{{sfn|Kidd|2013|pp=208–213}} Some scholars say that this letter was never actually dispatched, but was set aside and that the papal reply actually sent was the softer but still harsh letter ''Scripta tuae'' of January 1054.{{sfn|Setton|Baldwin|1969|pp=209–210}}

The advance of the [[Norman conquest of southern Italy]] constituted a threat to the possessions of both the Byzantine Empire and the papacy, each of which sought the support of the other. Accordingly, conciliatory letters, the texts of which have not been preserved, were written to the pope by the emperor and Cerularius. In his January 1054 reply to the emperor, ''Quantas gratias'',{{sfn|Migne|1882|pp=744–769}} Leo IX asked for his assistance against the [[Italo-Normans|Normans]] and complained of what the pope saw as Caerularius's arrogance. In his reply to Caerularius,{{sfn|Migne|1882|pp=773–777}} he upbraided the patriarch for trying to subject the patriarchs of Alexandria and Antioch to himself and for adopting the title of Ecumenical Patriarch and insisted on the primacy of the see of Rome.{{sfn|Kidd|2013|pp=208–213}}
{{multiple image
| direction = vertical
| width = 300
| footer =
| image1 = Expansion of christianity.jpg
| alt1 =
| caption1 = The division between the Eastern and Western Churches{{sfn|Smith|1915|loc=Plate 58A}}
}}

These two letters were entrusted to a delegation of three legates, headed by the undiplomatic cardinal [[Humbert of Silva Candida]], and also including [[Frederick of Lorraine (cardinal)|Frederick of Lorraine]], who was papal secretary and [[Cardinal-Deacon]] of [[Santa Maria in Domnica]], and Peter, [[Roman Catholic Archdiocese of Amalfi|Archbishop of Amalfi]]. They were given friendship and support by the emperor but were spurned by the patriarch. On 16 July 1054, three months after Pope Leo's death in April 1054 and nine months before the next pope took office,{{sfn|Setton|Baldwin|1969|pp=209–210}} they laid on the altar of [[Hagia Sophia]], which was prepared for the celebration of the [[Divine Liturgy]], a bull of excommunication of Cerularius and his supporters. At a synod held on 20 July 1054, Cerularius in turn excommunicated the legates.{{sfn|Kidd|2013|pp=208–213}}{{sfn|Previté-Orton|1975|p=276}}

===East and West since 1054===
There was no single event that marked the breakdown. Rather, the two churches slid into and out of schism over a period of several centuries, punctuated with temporary reconciliations. Efforts were made in subsequent centuries by emperors, popes and patriarchs to heal the rift between the churches. However, a number of factors and historical events worked to widen the separation over time.{{sfn|Jeffreys|Haldon|Cormack|2008|p=596}} It is estimated that in 1054, a slim majority of [[Christendom|Christians worldwide]] were [[Eastern Christianity|Eastern Christians]]; most of the rest were Western Christians.<ref>{{cite book |title=The Future of the Global Church: History, Trends and Possibilities |first=Patrick |last=Johnstone |year=2014 |publisher=InterVarsity Press |pages=100, 115}}</ref> Few of these would have noticed any difference as noted by Timothy Ware: "Even after 1054 friendly relations between East and West continued. The two parts of Christendom were not yet conscious of a great gulf of separation between them. ... The dispute remained something of which ordinary Christians in East and West were largely unaware".{{sfn|Ware|1963|p=67}}

At the time of the excommunications, many contemporary historians, including Byzantine chroniclers, did not consider the event significant.{{sfn|Binns|2002|p=203}}{{sfn|Dvorník|1945|pp=29–30|ps=: In spite of what happened in 1054, the faithful of both church remained long unaware of any change in their relations and acts of intercommunion were so numerous that 1054 as the date of the schism becomes inadmissible.}}{{sfn|King|2006|p=6}}{{sfn|Ware|1963|p=67}} Relations continued as usual, for instance [[Financial endowment|endownments]] made towards churches in the East such as the Holy Sepulchre were kept in place and Pope Gregory VII confirmed the proprietorship of the Patriarch of Jerusalem over a church in Le Marche in the Pyrenees.<ref>{{cite book |last1=Pohl |first1=Walter |last2=Kramer |first2=Rutger |title=Empires and Communities in the Post-Roman and Islamic World, C. 400-1000 CE |date=2021 |publisher=Oxford University Press |isbn=978-0-19-006794-6 |pages=214 |url=https://books.google.com/books?id=h3BEEAAAQBAJ |access-date=19 January 2024 |language=en}}</ref> 

When Emperor [[Alexios I Komnenos|Alexios Komnenos]] asked in the 1080s whether a canonical decision had been made to break relations with Rome, the participants of the synod of Constantinople said no.<ref>{{cite book |last1=Stopka |first1=Krzysztof |title=Armenia Christiana: Armenian Religious Identity and the Churches of Constantinople and Rome (4th–15th Century) Volumen 8 de Jagiellonian Studies in History |date=2016 |publisher=Wydawnictwo UJ |isbn=978-8323395553 |page=109 |url=https://books.google.com/books?id=eeq-DQAAQBAJ |access-date=25 December 2022}}</ref> Interactions in the 12th century between the Latin crusaders and the indigenous population show that rather than the former considering the latter as heretics or schismatics, they incorporated local hierarchies into their own.<ref name="MacEvitt">{{cite book |last1=MacEvitt |first1=Christopher |title=The Crusades and the Christian World of the East: Rough Tolerance |date=24 November 2010 |publisher=University of Pennsylvania Press |isbn=978-0-8122-0269-4 |pages=111–114 |url=https://books.google.com/books?id=Dh6RNqI0uikC |access-date=9 January 2024 |language=en}}</ref>

===Sectarian tensions in the Byzantine Empire in the 11th–12th centuries===
Starting from the late 11th century, the dependency of the Byzantine Empire on the navies of the [[Republic of Venice]] and, to a lesser extent, the [[Republic of Genoa]] and the [[Republic of Pisa]], led to the predominance of Catholic merchants in Byzantium—which had received major trading concessions since the 1080s—subsequently causing economic and social upheaval. Together with the perceived arrogance of the Italians, it fueled popular resentment amongst the middle and lower classes both in the countryside and in the cities.{{sfn|Fossier|1986|pp=506–508}}

By the second half of the 12th century, the practically uncontrollable rivalry among competitors from the different city-states devolved to the point that Italians were raiding the quarters of other Italians in the capital, and retaliatory draconian measures by the Byzantine authorities led to the deterioration of inter-religious relations in the city.

When in 1182 the regency of the [[empress mother]], [[Maria of Antioch]], an ethnic French notorious for the favouritism shown to Latin merchants and the big aristocratic land-owners, was deposed by [[Andronikos I Komnenos]] in the wake of popular support, the new emperor allowed mobs to [[Massacre of the Latins|massacre the hated foreigners]]. Henceforth Byzantine foreign policy was invariably perceived as sinister and anti-Latin in the West.{{sfn|Harris|2006|p=112}} Byzantine theologian [[Theodore Balsamon]] wrote in 1190 that no Latin should be given sacraments unless he first declares that he will abstain from Latin dogmas and customs and conform to Eastern practices. He was still criticized for excessive harshness by contemporaries such as Archbishop [[Demetrios Chomatenos]], who pointed out that Latins had not been condemned as heretics and were not in complete schism, although he did not state whether Latins should be given Communion or vice versa.<ref>{{cite book|last=Andrew P. Roach, James R. Simpson |title=Heresy and the Making of European Culture: Medieval and Modern Perspectives|date=2016|publisher=Routledge|isbn=9781317122500|page=42}}</ref>

===Fourth Crusade (1204) and other military conflicts===
{{Main|Fourth Crusade|Sack of Constantinople|Northern Crusades}}
{{See also|Massacre of the Latins}}
Motivated in part by lingering resentment over the [[massacre of the Latins]] in Constantinople 22 years earlier, ill-fated dynamics in the organization of the crusade (originally intended to recapture Jerusalem), and [[Alexios IV Angelos|Alexios Angelos']] request that his father's rule be reestablished in Constantinople, the fourth crusader army arrived in Constantinople in April of 1203. Latin crusaders and Venetian merchants sacked [[Constantinople]] itself (1204), looting [[Hagia Sophia|the Church of Holy Wisdom]] and various other Orthodox holy sites,{{sfn|Schaff|1913|p=320}} and converting them to Latin Catholic worship. The Norman Crusaders also destroyed the [[Imperial Library of Constantinople]].{{sfn|Howard|2011|p=21}}{{sfn|Murray|2009|p=53}}{{sfn|Bradford|2013|p=3}} 

Various holy artifacts from these Orthodox holy places were taken to the West. The crusaders also appointed a [[Latin Patriarch of Constantinople]].{{sfn|Schaff|1913|p=320}} The conquest of Constantinople and the [[Partitio terrarum imperii Romaniae|final treaty]] established the [[Latin Empire|Latin Empire of the East]] and the Latin Patriarch of Constantinople, with various other [[Crusader states]]. Later some religious artifacts were sold in Europe to finance or fund the Latin Empire in Byzantium – as when Emperor [[Baldwin II of Constantinople]] ({{reign | 1228 | 1261}}) sold the relic of the [[Crown of Thorns#Byzantium|Crown of Thorns]] while in France trying to raise new funds to maintain his hold on Byzantium.{{sfn|Nicol|1993|p=169}} 

In 1261, the Byzantine emperor, [[Michael VIII Palaiologos]] brought the Latin Empire to an end. However, the Western attack on the heart of the Byzantine Empire is seen{{by whom|date=April 2019}} as a factor that led eventually to its conquest by Ottoman Muslims in the 15th century.{{citation needed|date=July 2020}} Some scholars{{Who|date=March 2025}} believe that the 1204 sacking of Constantinople contributed more to the schism than the events of 1054.<ref>{{cite book|author=A. Edward Siecienski|title=Orthodox Christianity: A Very Short Introduction|date=2019|url=https://books.google.com/books?id=086aDwAAQBAJ&q=hagia+sophia+prostitute+1204&pg=PA24|page=24|publisher=[[Oxford University Press]]|isbn=978-0190883294}}</ref>

In northern Europe, the [[Teutonic Knights]], after their 12th- and 13th-century successes in the [[Northern Crusades]],{{sfn|Christiansen|1997|p=287}} attempted (1240) to conquer the [[Eastern Orthodox Church|Eastern Orthodox]] Russian Republics of [[Pskov Republic|Pskov]] and [[Novgorod Republic|Novgorod]], an enterprise somewhat endorsed by [[Pope Gregory IX]]{{sfn|Christiansen|1997|p=287}} ({{reign | 1227 | 1241}}). One of the major defeats the Teutonic Knights suffered was the [[Battle of the Ice]] in 1242. Catholic [[Sweden]] also undertook several [[Swedish-Novgorodian Wars|campaigns against Orthodox Novgorod]]. There were also [[List of armed conflicts involving Poland against Russia|conflicts]] between Catholic [[Poland]] and Orthodox Russia, which helped solidify the schism between East and West.

===Second Council of Lyon (1272)===
The [[Second Council of Lyon]] was convoked to act on a pledge by Michael VIII to reunite the Eastern church with the West.{{sfn|Wetterau|1994}} Wishing to end the Great Schism that divided [[Rome]] and [[Constantinople]], Gregory X had sent an embassy to Michael VIII, who had reconquered Constantinople, putting an end to the remnants of the [[Latin Empire]] in the East, and he asked Latin despots in the East to curb their ambitions.

On 29 June (the [[Feast of Saints Peter and Paul]], a patronal feast of the Popes), Gregory X celebrated a [[Mass (liturgy)|Mass]] in [[Lyon Cathedral|St John's Church]], where both sides took part. The council declared that the Roman church possessed "the supreme and full primacy and authority over the universal Catholic Church."

The union effected was "a sham and a political gambit", a fiction maintained by the emperor to prevent westerners from recovering the city of Constantinople, which they had lost just over a decade before, in 1261.{{sfn|Nicol|1996|p=38}}{{sfn|Previté-Orton|1975|p=735}}{{sfn|Nicol|1993|p=63}} It was fiercely opposed by clergy and people{{sfn|Nicol|1993|p=79}}{{sfn|Previté-Orton|1975|p=735}} and never put into effect,{{sfn|Treadgold|1973|p=2}} in spite of a sustained campaign by Patriarch [[John XI of Constantinople]] (John Bekkos), a convert to the cause of union, to defend the union intellectually, and vigorous and brutal repression of opponents by Michael.{{sfn|Nicol|1993|p=79}}{{sfn|Schaff|1910a|loc=§18 The Council of Ferrara–Florence. 1438–1445}} 

In 1278, [[Pope Nicholas III]], learning of the fictitious character of Greek conformity,{{sfn|Nicol|1993|p=72}} sent legates to Constantinople, demanding the personal submission of every Orthodox cleric and adoption of the ''Filioque'',{{sfn|Siecienski|2010|p=140}} as already the Greek delegates at Lyon had been required to recite the Creed with the inclusion of ''Filioque'' and to repeat it two more times.{{sfn|Siecienski|2010|p=137}} 

Emperor Michael's attempts to resolve the schism ended when [[Pope Martin IV]], seeing that the union was only a sham, excommunicated Michael VIII in 1281 in support of [[Charles of Anjou]]'s attempts to mount a new campaign to retake the Eastern Roman provinces lost to Michael.{{sfn|Nicol|1993|p=79}}{{sfn|Williams|2004|p=37}}{{sfn|Penn|2007|p=134}}{{sfn|Hughes|1979|p=29}}{{sfn|Bunson|2004|p=24}}{{sfn|Nicol|1971|p=136}}{{sfn|Walsh|2006|p=107}}{{sfn|Ott|1910}} Michael VIII's son and successor [[Andronikos II Palaiologos|Andronicus II]] repudiated the union, and Bekkos was forced to abdicate, being eventually exiled and imprisoned until his death in 1297.

===Council of Ferrara–Florence (1439)===
{{Further|Council of Florence|Bull of Union with the Greeks}}
In the 15th century, the eastern emperor [[John VIII Palaiologos]], pressed hard by the [[Ottoman Turks]], was keen to ally himself with the West, and to do so he arranged with [[Pope Eugene IV]] for discussions about the reunion to be held again, this time at the [[Council of Ferrara-Florence]]. After several long discussions, the emperor managed to convince the Eastern representatives to accept the Western doctrines of Filioque, Purgatory and the supremacy of the Papacy. On 6 June 1439, an agreement was signed by all the Eastern bishops present but one, [[Mark of Ephesus]], who held that Rome continued in both [[heresy]] and [[Schism (religion)|schism]]. 

It seemed that the Great Schism had been ended. Upon their return, the Eastern bishops found their agreement with the West broadly rejected by the populace and by civil authorities, with the notable exception of the Emperors of the East who remained committed to union until the [[Fall of Constantinople]] two decades later. The union signed at Florence has never been accepted by the Eastern churches.

===Fall of Constantinople (1453) and thereafter===
At the time of the [[Fall of Constantinople]] to the invading [[Ottoman Empire]] in May 1453, Orthodox Christianity was already entrenched in [[Russia]], whose political and de facto religious centre had shifted from [[Kiev]]<!--See WP:KIEV--> to [[Moscow]]. The [[Russian Orthodox Church|Russian Church]], a part of the Church of Constantinople until the mid-15th century, was granted full independence ([[autocephaly]]) and elevated to the rank of [[Patriarch of Moscow and all Rus'|Patriarchate]] in 1589. The Russian political and ecclesiastical elite came to view Moscow as the [[Third Rome]], a legitimate heir to Constantinople and Byzantium.{{sfn|Nicol|1993|p=72}}

Under [[Ottoman Empire|Ottoman]] rule, the Orthodox Church acquired the status of an autonomous [[Millet (Ottoman Empire)|millet]], specifically the [[Rum Millet]]. The Ecumenical Patriarch became the ruler ([[Ethnarch|millet başı]]) of all the Orthodox Christian subjects of the empire, including non-Greeks. Upon conquering Constantinople, [[Mehmed II]] assumed the legal function of the Byzantine emperors and appointed Patriarch [[Gennadius II]]. The sultans enhanced the temporal powers of the Greek orthodox hierarchy that came to be politically beholden solely to the Ottoman sultan and, along with other [[Ottoman Greek]] [[Phanariotes|nobles]], came to run the Balkan Orthodox domains of the Ottoman Empire.{{sfn|Thornton|1854|p=3}}{{sfn|Mouravieff|1842|p=165}}

In Russia, the anti-Catholic sentiments came to be entrenched by the [[Polish–Muscovite War (1605–1618)|Polish intervention]] during the [[Time of Troubles]] in the early 17th century, which was seen as an attempt to convert Moscow to Catholicism. The modern Russian national holiday, [[Unity Day (Russia)|Unity Day]], was established on the day of church celebration in honour of the [[Our Lady of Kazan]] icon, which is believed to have miraculously saved Moscow from outright Polish conquest in 1612. [[Patriarch Hermogenes of Moscow]] was executed by the Poles and their supporters during this period (see also [[Polish–Lithuanian–Muscovite Commonwealth]]).{{sfn|Thornton|1854|p=3}}{{sfn|Mouravieff|1842|p=165}}

In the 16th and 17th centuries, there were attempts at unions between the Roman Church and various groups within Eastern Orthodoxy. For example, a succession of Patriarchs of Antioch had been in communion with both Rome and Constantinople in the years preceding the Rome-Antioch schism of 1724.<ref>Sebastian Carnazzo, "Melkite Christians," in The Rowman & Littlefield Handbook of Christianity in the Middle East, 2020, p. 271.</ref> 
The final separation between the Catholic Church and the Eastern Orthodox Churches came in the 18th century. In 1729, the Roman Church under [[Pope Benedict XIII]] prohibited communion with Orthodox Churches. In 1755, the patriarchs of Alexandria, Jerusalem and Constantinople in retaliation declared the final interruption of sacral communion with the Roman Church and declared Catholicism heretical.<ref>Encyclopedia Britannica, "Orthodoxy under the Ottomans (1453–1821). Relations with the West"</ref>

===First Vatican Council (1870)===
The doctrine of papal primacy was further developed at the [[First Vatican Council]], which declared that "in the disposition of God the Roman church holds the preeminence of ordinary power over all the other churches". This council also affirmed the dogma of [[papal infallibility]], declaring that the infallibility of the Christian community extends to the pope himself when he defines a doctrine concerning faith or morals to be held by the whole Church. This new dogma, as well as the dogma of the Immaculate Conception, promulgated in ''[[Ineffabilis Deus]]'' a few years prior, are unequivocally rejected by the Eastern Church as heretical.<ref name="encyc1848" />{{Not in refs|date=May 2019}}

===Nullification of mutual anathemas (1965)===
A major event of the [[Second Vatican Council]] (Vatican II), was the issuance by [[Pope Paul VI]] and Orthodox Patriarch [[Athenagoras I of Constantinople]] of the [[Catholic–Orthodox Joint Declaration of 1965]]. At the same time, they lifted the mutual excommunications dating from the 11th century.{{sfn|Paul VI|1965}} The act did not result in the restoration of communion.

==Eastern Catholic Churches==
{{Main|Eastern Catholic Churches}}{{See also|Code of Canons of the Eastern Churches|Union of Brest|Union of Uzhhorod}}The [[Eastern Catholic Churches]], historically referred to as "uniate" by the Orthodox, consider themselves to have reconciled the East and West Schism by having accepted the primacy of the Bishop of Rome while retaining some of the canonical rules and liturgical practices in line with the Eastern tradition such as the [[Byzantine Rite]] that is prevalent in the Orthodox Churches. Some Eastern Orthodox charge that joining in this unity comes at the expense of ignoring critical doctrinal differences and past atrocities.

There have been periodic conflicts between the Orthodox and Eastern Catholics in [[Ukraine]] and [[Belarus]], then under [[Poland|Polish]] rule,{{sfn|Pospielovsky|1998|p=96}} and later also in [[Transylvania]] (see the [[Romanian Greek Catholic Church United with Rome]]). Pressure and government-sponsored reprisals were used against Eastern Catholic Churches such as the [[Ukrainian Greek Catholic Church]] in the Russian Empire and later in the [[Soviet Union]].<ref name="risu.org.ua" /> Since the late 1980s, the Moscow Patriarchate (the [[Russian Orthodox Church]]) has criticised the methods of restoration of the "uniate" church structures in Ukraine as well as what it called Catholic [[proselytism]] in Russia.{{sfn|Dikarev|2010}}

In 1993, a [[Balamand declaration|report]] written by the [[Joint International Commission for Theological Dialogue Between the Catholic Church and the Orthodox Church]] during its 7th plenary session at the [[University of Balamand|Balamand School of Theology]] in [[Lebanon]] stated:<ref name="Balamand1993" />{{efn|The report contains unofficial suggestions of the commission, "until the competent organs of the Catholic Church and of the Orthodox Churches express their judgement in regard to it."<ref name="Balamand1993" />}} "Because of the way in which Catholics and Orthodox once again consider each other in their relationship to the mystery of the Church and discover each other once again as Sister Churches, this form of 'missionary apostolate' described above, and which has been called '[[Eastern Catholic Churches|uniatism]]', can no longer be accepted either as a method to be followed nor as a model of the unity our Churches are seeking". At the same time, the document inter alia stated:
* Concerning the Oriental Catholic Churches, it is clear that they, as part of the Catholic Communion, have the right to exist and to act in answer to the spiritual needs of their faithful.
* The Oriental Catholic Churches who have desired to re-establish full communion with the See of Rome and have remained faithful to it, have the rights and obligations which are connected with this communion. The principles determining their attitude towards Orthodox Churches are those which have been stated by the Second Vatican Council and have been put into practice by the Popes who have clarified the practical consequences flowing from these principles in various documents published since then. These Churches, then, should be inserted, on both local and universal levels, into the dialogue of love, in mutual respect and reciprocal trust found once again, and enter into the theological dialogue, with all its practical implications.

In February 2016, [[Pope Francis]] and [[Patriarch Kirill]] of the Russian Orthodox Church (ROC), had a meeting in [[Cuba]] and signed a [[Joint Declaration of Pope Francis and Patriarch Kirill|joint declaration]] that stated inter alia: "It is our hope that our meeting may also contribute to reconciliation wherever tensions exist between Greek Catholics and Orthodox. It is today clear that the past method of 'uniatism', understood as the union of one community to the other, separating it from its Church, is not the way to re-establish unity. Nonetheless, the ecclesial communities which emerged in these historical circumstances have the right to exist and to undertake all that is necessary to meet the spiritual needs of their faithful, while seeking to live in peace with their neighbours. Orthodox and Greek Catholics are in need of reconciliation and of mutually acceptable forms of co-existence."<ref name="bbcnews2016-02-13" /><ref name="VIS2016" /><ref name="KirillFrancis" /> 

Meanwhile, in the interview published on the eve of the meeting in Cuba, Metropolitan [[Hilarion (Alfeyev)|Hilarion Alfeyev]], the chairman of the [[Department of External Church Relations]] and a permanent member of the [[Holy Synod of the ROC]], said that tensions between the [[Ukrainian Greek Catholic Church]] and the [[Ukrainian Orthodox Church (Moscow Patriarchate)|ROC's Ukrainian Orthodox Church]] had been recently heightened mainly due to the [[Russo-Ukrainian war]].<ref name="alfeevinterv" /> The declaration was sharply criticised by [[Sviatoslav Shevchuk]], the Primate of the Ukrainian Greek Catholic Church, who said that his flock felt "betrayed" by the Vatican.<ref name="hurriyetdailynews.com" />{{sfn|Olson|2016}}<ref name="newsrushevchuk" />

==Recent efforts at reconciliation==

===Joint Theological Commission===
Inspired by Vatican II that adopted the ''[[Unitatis Redintegratio]]'' decree on [[ecumenism]] in 1964 as well as the change of heart toward Ecumenism on the part of the Moscow Patriarchate that had occurred in 1961, the Vatican and 14 universally recognised autocephalous Orthodox Churches established the [[Joint International Commission for Theological Dialogue Between the Catholic Church and the Orthodox Church]] that first met in Rhodes in 1980 and is an ongoing endeavour.

===Other moves toward reconciliation===
On a number of occasions, [[Pope John Paul II]] recited the Nicene Creed with patriarchs of the [[Eastern Orthodox Church]] in Greek according to the original text.<ref name="usccb.org" /> Both he and his successor, [[Pope Benedict XVI]], have recited the Nicene Creed jointly with Patriarchs [[Patriarch Demetrius I of Constantinople|Demetrius I]] and [[Bartholomew I]] in Greek without the ''Filioque'' clause, "according to the usage of the Byzantine Churches".<ref name="vati_Sole" /><ref name="youtube" /> This accords with the Catholic Church's practice of including the clause when reciting the Creed in Latin,<ref>Missale Romanum 2002 (Roman Missal in Latin), p. 513</ref> but not when reciting it in Greek.<ref name="autogenerated347">Ρωμαϊκό Λειτουργικό 2006 (Roman Missal in Greek), vol. 1, p. 347</ref>

In June 1995, [[Patriarch Bartholomew I]], of Constantinople, visited [[Vatican City]] for the first time, and joined in the historic inter-religious day of prayer for peace at [[Assisi]]. John Paul II and Bartholomew I explicitly stated their mutual "desire to relegate the excommunications of the past to oblivion and to set out on the way to re-establishing full communion".{{sfn|John Paul II|2004}}

In May 1999, John Paul II was the first pope since the Great Schism to visit an Eastern Orthodox country: [[Romania]]. Upon greeting John Paul II, the Romanian Patriarch [[Teoctist Arăpaşu|Teoctist]] stated: "The second millennium of Christian history began with a painful wounding of the unity of the Church; the end of this millennium has seen a real commitment to restoring Christian unity." John Paul II visited other heavily Orthodox areas such as [[Ukraine]], despite lack of welcome at times, and he said that healing the divisions between Western and Eastern Christianity was one of his fondest wishes.

In June 2004, Bartholomew I's visit to Rome for the [[Feast of Saints Peter and Paul]] (29 June) afforded him the opportunity for another personal meeting with John Paul II, for conversations with the [[Pontifical Council for Promoting Christian Unity]] and for taking part in the celebration for the feast day in [[St. Peter's Basilica]].

The Patriarch's partial participation in the Eucharistic liturgy at which the Pope presided followed the program of the past visits of Patriarch Dimitrios (1987) and [[Patriarch Bartholomew I]] himself: full participation in the [[Liturgy of the Word]], a joint proclamation by the Pope and by the Patriarch of the profession of faith according to the [[Nicene-Constantinopolitan Creed]] in Greek and as the conclusion, the final Blessing imparted by both the Pope and the Patriarch at the Altar of the Confessio.{{sfn|Fortino|2005|p=11}} The Patriarch did not fully participate in the Liturgy of the Eucharist involving the consecration and distribution of the [[Eucharist]] itself.{{sfn|John Paul II|2004}}

==Prospects for reconciliation==

Despite efforts on the part of Catholic popes and Orthodox patriarchs to heal the schism, only limited progress towards reconciliation has been made over the last half-century. One stumbling block is the fact that the Orthodox and the Catholics have different perceptions of the nature of the divide. The official Catholic teaching is that the Orthodox are schismatic, meaning that there is nothing heretical about their theology, and their unwillingness to accept the [[Papal supremacy|supremacy of the Pope]] is presented in Catholic teaching as chiefly an ecclesiological issue, not so much a theological one. The Orthodox object to the Catholic doctrines of [[purgatory]], [[substitutionary atonement]], the [[Immaculate Conception|immaculate conception]], and [[papal supremacy]], among others, as heretical doctrines.<ref name="VatIns" /> With respect to primacy of the pope, the two churches agree that the pope, as Bishop of Rome, has primacy although they continue to have different interpretations of what that primacy entails.

The Catholic Church's attitude was expressed by John Paul II in the image of the Church "breathing with her two lungs".{{sfn|John Paul II|1995|loc=para 54}} He meant that there should be a combination of the more rational, juridical, organization-minded "Latin" temperament with the intuitive, mystical and contemplative spirit found in the East.{{sfn|Stanford|Hebblethwaite|Hebblethwaite|2005}}

In the Orthodox view, the Bishop of Rome (i.e. the Pope) would have universal primacy in a reunited Christendom, as ''[[primus inter pares]]'' without the power of jurisdiction.{{sfn|Clapsis|2005}}

===Ecclesiological reconciliation===

The Eastern Orthodox insist that the primacy is largely one of honor, the Pope being "[[first among equals]]" ''primus inter pares''. The Catholic Church, on the other hand, insists on the doctrine of supremacy. It is widely understood that, if there is to be reconciliation, both sides will have to compromise on this doctrine. Although some commentators have proposed ways in which such compromise can be achieved, there is no official indication that such compromise is being contemplated.

In his 1987 book ''Principles of Catholic Theology'', Pope Benedict XVI (then Cardinal Ratzinger) assessed the range of "possibilities that are open to Christian ecumenism." He characterized the "maximum demand" of the West as the recognition by the East of and submission to the "primacy of the bishop of Rome in the full scope of the definition of 1870..." The "maximum demand" of the East was described as a declaration by the West of the 1870 doctrine of papal primacy as erroneous along with the "removal of the Filioque from the Creed and including the Marian dogmas of the nineteenth and twentieth centuries." Ratzinger asserted that "(n)one of the maximum solutions offers any real hope of unity."{{sfn|Cleenewerck|2007|p=120}} 

Ratzinger wrote that "Rome must not require more from the East than had been formulated and what was lived in the first millennium." He concluded that "Reunion could take place in this context if, on the one hand, the East would cease to oppose as heretical the developments that took place in the West in the second millennium and would accept the Catholic Church as legitimate and orthodox in the form she had acquired in the course of that development, while on the other hand, the West would recognize the Church of the East as orthodox in the form she has always had."{{sfn|Ratzinger|Boeve|Mannion|2010|p=162}}

The [[declaration of Ravenna]] in 2007 re-asserted the belief that the bishop of Rome is indeed the ''protos'', although future discussions are to be held on the concrete ecclesiological exercise of papal primacy.

===Theological reconciliation===

{{more citations needed section|date=October 2012}}

Some scholars such as Jeffrey Finch assert that "the future of East–West rapprochement appears to be overcoming the modern polemics of neo-scholasticism and neo-Palamism".{{sfn|Christensen|Wittung|2007|p=244}}

These doctrinal issues center around the Orthodox perception that the Catholic theologians lack the actual experience of God called ''[[theoria]]'' and thereby fail to understand the importance of the heart as a [[Nous|noetic]] or intuitive faculty. It is what they consider to be the Catholic Church's reliance on pagan metaphysical philosophy and rational methods such as [[scholasticism]] rather than on the intuitive experience of God (theoria) that causes Orthodox to consider the Catholic Church heretical. Other points of doctrinal difference include a difference regarding human nature as well as a difference regarding [[original sin]], purgatory, and the [[Hell in Christian beliefs|nature of Hell]].

One point of theological difference is embodied in the dispute regarding the inclusion of the ''Filioque'' in the Nicene Creed. In the view of the Catholic Church, what it calls the legitimate complementarity of the expressions "from the Father" and "from the Father and the Son" does not provide it does not become rigid, affect the identity of faith in the reality of the same mystery confessed.{{sfn|Catholic Church|1994|p=64|loc=para 248}}{{clarify|date=May 2021}} The Orthodox, on the other hand, view inclusion of the phrase to be almost heretical (see also the [[#Trinity|Trinity section]]).

More importantly, the Orthodox see the Filioque as just the tip of the iceberg and really just a symptom of a much more deeply rooted problem of theology, one so deeply rooted that they consider it to be heretical and even, by some characterizations, an inability to "see God" and know God. This heresy is allegedly rooted in [[Frankish mythology|Frankish paganism]], [[Arianism]], [[Platonism|Platonist]] and [[Aristotelianism|Aristotelian]] philosophy and [[Thomism|Thomist]] rational and objective Scholasticism. In opposition to what they characterize as pagan, heretical and "godless" foundations, the Orthodox rely on intuitive and mystical knowledge and vision of God (''theoria'') based on [[hesychasm]] and [[wikt:noesis|noesis]].{{Citation needed|date=February 2009}} Catholics accept as valid the Eastern Orthodox intuitive and mystical understanding of God and consider it complementary to the rational Western reflection.{{sfn|Stanford|Hebblethwaite|Hebblethwaite|2005}}{{sfn|Nichols|1996|pp=264–275}}

====Sacraments====
Most Orthodox Churches through [[Economy (religion)|economy]] do not require baptism in the Orthodox Church for one who has been previously baptized in the Catholic Church. Most Orthodox jurisdictions, based on that same principle of economy, allow a sacramental marriage between an Orthodox Christian and some non-Orthodox Christians.
The Catholic Church allows its clergy to administer the sacraments of Penance, the Eucharist and Anointing of the Sick to members of the Eastern Orthodox Church, if these spontaneously ask for the sacraments and are properly disposed.{{sfn|Cassidy|Duprey|1993}} 

It also allows Catholics who cannot approach a Catholic minister to receive these three sacraments from the clergy of the Eastern Orthodox Church, whenever necessity requires or a genuine spiritual advantage commends it, and provided the danger of error or indifferentism is avoided.{{sfn|Cassidy|Duprey|1993}} Catholic canon law allows marriage between a Catholic and an Orthodox.<ref name="CCEO#813" /> The Orthodox Church will only administer the sacraments to Christians who are not Orthodox if there is an emergency.

The Code of Canons of the Eastern Churches authorizes the local Catholic bishop to permit a Catholic priest, of whatever rite, to bless the marriage of Orthodox faithful who, being unable without great difficulty to approach a priest of their own Church, ask for this spontaneously.<ref name="CCEO#833" /> In exceptional circumstances Catholics may, in the absence of an authorized priest, marry before witnesses. If a priest who is not authorized for the celebration of the marriage is available, he should be called in, although the marriage is valid even without his presence.<ref name="CCEO#ChV" /> The Code of Canons of the Eastern Churches specifies that, in those exceptional circumstances, even a "non-Catholic" priest (and so not necessarily one belonging to an Eastern Church) may be called in.<ref name="CCEO#ChV" />

===Criticism of reconciliation efforts===

The efforts of Orthodox patriarchs towards reconciliation with the Catholic Church has been strongly criticized by some elements of Eastern Orthodoxy, such as the Metropolitan of Kalavryta, Greece, in November 2008.<ref name="mkka" />

In 2010, Patriarch [[Bartholomew I]] issued an encyclical lauding the ongoing dialogue between the Orthodox Church and other Christian churches and lamenting that the dialogues between the two churches were being criticized in "an unacceptably fanatical way" by some who claim to be defenders of Orthodoxy despite the fact that these dialogues are being conducted "with the mutual agreement and participation of all local Orthodox Churches". The Patriarch warned that "such opponents raise themselves above episcopal synods and risk creating schisms".<ref name="Catholic News Agency" /> A major point of contention in the way of ecumenical dialogue is the question of [[calendar reform]] in the Orthodox Church, particularly regarding the adoption of the [[Revised Julian calendar]] (heavily influenced by the [[Gregorian calendar]] of the West). Opponents of ecumenism within the Eastern Orthodox Church, using the pretext of calendar reform, have separated themselves into [[Old Calendarists|Old Calendarist]] groups. 

The Patriarch further accused some critics of distorting reality to "deceive and arouse the faithful" and of depicting theological dialogue not as a pan-Orthodox effort, but an effort of the Ecumenical Patriarchate alone. As an example, he pointed to "false rumors that union between the Roman Catholic and Orthodox Churches is imminent" claiming that the disseminators of such rumors were fully aware that "the differences discussed in these theological dialogues remain numerous and require lengthy debate". The Patriarch re-emphasized that "union is not decided by theological commissions but by Church Synods".<ref name="Catholic News Agency" />

== References ==
===Notes===
{{Notelist}}

===Citations===
{{Reflist|refs=

<ref name="oca.org">{{Cite web |title=Saint Metrophanes, first Patriarch of Constantinople |work=oca.org |access-date=2 March 2020 |url= https://www.oca.org/saints/lives/2020/06/04/101609-saint-metrophanes-first-patriarch-of-constantinople }}</ref>

<ref name="theotokos">{{Cite web |title=An Orthodox View of the Virgin Mary |work=orthodoxinfo.com |access-date=2 March 2020 |url= http://orthodoxinfo.com/inquirers/theotokos.aspx }}</ref>

<ref name="encyc_1895">{{Cite web |title=The Patriarchal Encyclical of 1895 |work=orthodoxinfo.com |access-date=3 March 2020 |url= http://orthodoxinfo.com/ecumenism/encyc_1895.aspx }}</ref>

<ref name="bbcnews2016-02-13">{{Cite web |title=Unity call as Pope Francis holds historic talks with Russian Orthodox Patriarch |work=BBC News |date=13 February 2016 |access-date=3 March 2020 |url= https://www.bbc.com/news/world-latin-america-35565085 }}</ref>

<ref name="VIS2016">{{Cite news |url=http://visnews-en.blogspot.com/2016/02/historic-encounter-between-pope-and.html |title=Historic encounter between the Pope and Patriarch of Moscow and All Russia: Orthodox and Catholics are brothers, not competitors |date=13 February 2016 |access-date=13 February 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160213144411/http://visnews-en.blogspot.com/2016/02/historic-encounter-between-pope-and.html |archive-date=13 February 2016 |publisher=Vatican Information Service |location=Vatican City |website=visnews-en.blogspot.com}} Includes full text of the Joint Declaration.</ref>

<ref name="hurriyetdailynews.com">{{Cite web |title=Ukrainian Greek Catholics 'betrayed' by pope-patriarch meeting |author=Agence France-Presse |work=Hürriyet Daily News |date=14 February 2016 |access-date=3 March 2020 |url= https://www.hurriyetdailynews.com/ukrainian-greek-catholics-betrayed-by-pope-patriarch-meeting--95183 }}</ref>

<ref name="KirillFrancis">{{Cite web |title=Совместное заявление Папы Римского Франциска и Патриарха Московского и всея Руси Кирилла |trans-title=Joint statement by Pope Francis and Patriarch of Moscow and All Russia Kirill |work=mospat.ru |date=13 February 2016 |access-date=4 March 2020 |url= https://mospat.ru/ru/2016/02/13/news128178/ |language=ru }}</ref>

<ref name="alfeevinterv">{{Cite news |url=http://kommersant.ru/doc/2913683 |date=11 February 2016 |publisher=[[Kommersant]] |language=ru |script-title=ru:"Противоречия полностью не преодолены":Глава церковного МИДа митрополит Иларион об отношениях между Московским патриархатом и Ватиканом |trans-title=Contradictions are not fully overcome ": Church Foreign Minister Metropolitan Hilarion on relations between the Moscow Patriarchate and the Vatican}}</ref>

<ref name="orthodoxeurope.org">{{Cite web |title=Ecclesiological and Canonical Consequences of the Sacramental Nature of the Church. Ecclesial Communion, Conciliarity and Authority |location=Ravenna |date=13 October 2007 |work=Europaica Bulletin |publisher=Department for External Church Relations of the Moscow Patriarchate |access-date=4 March 2020 |url= http://orthodoxeurope.org/page/14/130.aspx#2 }}</ref>

<ref name="encyc1848">{{Cite web |url=https://sourcebooks.fordham.edu/mod/1848orthodoxencyclical.asp |title=Encyclical of the Eastern Patriarchs, 1848 : A Reply to the Epistle of Pope Pius IX, "to the Easterns" |website=sourcebooks.fordham.edu |access-date=27 May 2019}}</ref>

<ref name="youtube">{{youTube|id=_MFg8FBOHDg |title=Benedict XVI and Bartholomew I recite the Creed in Greek}}
</ref>

<ref name="orthodoxytoday.org2005.02.01">{{Cite web |title=A Letter To The Ecumenical Patriarch Concerning The Situation Of The Diaspora |author=Patriarch Alexis of Moscow and All Russia |work=orthodoxytoday.org |date=1 February 2005 |access-date=7 March 2020 |url= http://www.orthodoxytoday.org/articles-2009/Alexis-A-Letter-To-The-Ecumenical-Patriarch-Concerning-The-Situation-Of-The-Diaspora.php }}</ref>

<ref name="Balamand1993">{{cite conference |date=1993-06-24 |section=Communiqué |title=Uniatism, method of union of the past, and the present search for full communion |conference=Joint International Commission for the Theological Dialogue between the Roman Catholic Church and the Orthodox Church: 7th plenary session, June 17–24, 1993, Balamand, Lebanon |location=Vatican City |section-url=https://www.vatican.va/roman_curia/pontifical_councils/chrstuni/ch_orthodox_docs/rc_pc_chrstuni_doc_19930624_lebanon_en.html |archive-url=https://web.archive.org/web/20031223144638/https://www.vatican.va/roman_curia/pontifical_councils/chrstuni/ch_orthodox_docs/rc_pc_chrstuni_doc_19930624_lebanon_en.html |archive-date=2003-12-23 |url-status=live}}</ref>

<ref name="patriarchate.org">{{cite web|title=History of the Ecumenical Patriarchate|url=http://www.patriarchate.org/patriarchate/history |archive-url=https://web.archive.org/web/20100510123826/http://www.patriarchate.org/patriarchate/history |website=The Ecumenical Patriarchate of Constantinople |archive-date=10 May 2010 |url-status=dead}}</ref>

<ref name="orthodox.org.ph">{{Cite web |url=http://www.orthodox.org.ph/content/view/211/50/ |title=Orthodox Church in the Philippines – East–West Schism 01 |publisher=Orthodox.org.ph |url-status=dead |archive-url=https://archive.today/20120905202235/http://www.orthodox.org.ph/content/view/211/50/ |archive-date=5 September 2012 |access-date=23 February 2013}}</ref>

<ref name="VatIns">{{cite news|url=http://vaticaninsider.lastampa.it/en/world-news/detail/articolo/ortodossi-ortodoxa-orthodox-francesco-francisco-francis-33491/|archive-url=https://web.archive.org/web/20170204145627/http://www.lastampa.it/2014/04/15/vaticaninsider/eng/world-news/two-orthodox-bishops-accuse-the-pope-of-heresy-j7zbqqHM2yGhCPRlbrqHlM/pagina.html|archive-date=4 February 2017 |newspaper=Vatican Insider|title=Two Orthodox bishops accuse the Pope of heresy|date=15 April 2014|via=La Stampa}}</ref>

<ref name="Catholic News Agency">{{Cite news |url=https://www.catholicnewsagency.com/news/18753/patriarch-of-constantinoples-new-encyclical-defends-catholic-orthodox-dialogue |title=Patriarch of Constantinople's new encyclical defends Catholic-Orthodox dialogue |date=20 February 2010 |newspaper=Catholic News Agency |access-date=27 January 2011}}</ref>

<ref name="Unitatis Redintegratio">{{Citation |author=Pope Paul VI|author-link=Pope Paul VI |title=Decree on Ecumenism : Unitatis Redintegratio |url=https://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_decree_19641121_unitatis-redintegratio_en.html |at=n. 17 |place=Rome |publisher=The Vatican |date=21 November 1964}}</ref>

<ref name="vati_Sole">{{Cite web |title=Presentation of the Celebration |work=vatican.va |date=29 June 2004 |access-date=9 March 2020 |url= https://www.vatican.va/news_services/liturgy/2004/documents/ns_lit_doc_20040629_rite_en.html |quote=Solemnity of the Feast of St. Peter and St. Paul (June 29, 2004) }}</ref>

<ref name="PCPCU">{{cite news|archive-url=https://web.archive.org/web/20091026205632/http://www.geocities.com/trvalentine/orthodox/vatican_clar_images.html |title=The Greek and the Latin Traditions regarding the Procession of the Holy Spirit|newspaper=L'Osservatore Romano|date=20 September 1995|url=http://www.geocities.com/trvalentine/orthodox/vatican_clar_images.htm|archive-date=2009-10-26}}</ref>

<ref name="newsrushevchuk">{{Cite news |url=http://newsru.com/religy/15feb2016/shevchuk.html |date=15 February 2016 |publisher=[[NEWSru]] |language=ru |script-title=ru:Украинские греко-католики чувствуют себя преданными Ватиканом Подробнее|trans-title=Ukrainian Greek Catholics feel betrayed by the Vatican}}</ref>

<ref name="usccb.org">{{cite web|url=http://www.usccb.org/beliefs-and-teachings/dialogue-with-others/ecumenical/orthodox/filioque-church-dividing-issue-english.cfm |title=The Filioque: A Church Dividing Issue?: An Agreed Statement
 |access-date= 17 October 2012|archive-url=https://web.archive.org/web/20120307153427/http://www.usccb.org/beliefs-and-teachings/dialogue-with-others/ecumenical/orthodox/filioque-church-dividing-issue-english.cfm |archive-date=2012-03-07|date=October 25, 2003|website=United States Conference of Catholic Bishops}}</ref>

<ref name="Romanides_Filioque">{{Cite web |url=http://www.geocities.com/trvalentine/orthodox/romanides_filioque.html |title=Filioque |last=Romanides |first=John S. |url-status=dead |archive-url=https://web.archive.org/web/20090729230350/http://www.geocities.com/trvalentine/orthodox/romanides_filioque.html |archive-date=29 July 2009 }}</ref>

<ref name="Franks">{{Cite book |url=http://www.romanity.org/htm/rom.03.en.franks_romans_feudalism_and_doctrine.02.htm |title=Franks, Romans, Feudalism, and Doctrine – Part 2. Empirical Theology versus Speculative Theology – Empirical Theology |last=Romanides |first=John S. }}</ref>

<ref name="OrthodoxCatechism#53">{{Cite web |title=An Online Orthodox Catechism |work=Department for External Church Relations of the Moscow Patriarchate |access-date=9 March 2020 |url= http://orthodoxeurope.org/page/10/1.aspx#53 }}</ref>

<ref name="OrthodoxCatechism#24">{{Cite web |title=An Online Orthodox Catechism |work=Department for External Church Relations of the Moscow Patriarchate |access-date=9 March 2020 |url= http://orthodoxeurope.org/page/10/1.aspx#24 }}</ref>

<ref name="Guimarães">{{cite web|last=Guimarães |first=Atila Sinke |title=Curiosities from the 'Orthodox' Arena |url=http://www.traditioninaction.org/HotTopics/b004bht.htm |website=Tradition in Action}}</ref>

<ref name="kaldu.org">{{cite web|url=http://www.kaldu.org/14_Reformed_ChaldeanMass/QA_NewMass.html |title=Q & A on the Reformed Chaldean Mass|archive-url=https://web.archive.org/web/20090102212208/http://www.kaldu.org/14_Reformed_ChaldeanMass/QA_NewMass.html |archive-date=2 January 2009}}</ref>

<ref name="CCEO#813">{{Cite web |title= Canon 813|work=Code of Canons of Oriental Churches |date=2007 |access-date=9 March 2020 |url= http://www.intratext.com/IXT/ENG1199/_PML.HTM}}</ref>

<ref name="CCEO#833">{{Cite web |title= Canon 833|work=Code of Canons of Oriental Churches |date=2007 |access-date=9 March 2020 |url= http://www.intratext.com/IXT/ENG1199/_PN5.HTM}}</ref>

<ref name="CCEO#ChV">{{Cite web |title= Chapter V : The Form of the Celebration of Marriage|work=Code of Canons of Oriental Churches |date=2007 |access-date=9 March 2020 |url= http://www.intratext.com/IXT/ENG0017/_P3Z.HTM}}</ref>

<ref name="CCEO#181">{{Cite web |title= Canon 181|work=Code of Canons of Oriental Churches |date=2007 |access-date=9 March 2020 |url= http://www.intratext.com/IXT/ENG1199/_P51.HTM}}</ref>

<ref name="CCEO#844">{{Cite web |title= Canon 844 §3|work=Code of Canons of Oriental Churches |date=2007 |access-date=9 March 2020 |url= http://www.intratext.com/IXT/ENG1199/_P51.HTM}}</ref>

<ref name="VaticanI">{{Cite web |url=http://www.ewtn.com/library/COUNCILS/V1.htm#6 |title=Dogmatic Constitution on the Church of Christ, Chapter 4 – On Faith and Reason|website=First Vatican Council (1869–1870)|archive-url=https://web.archive.org/web/20060207151342/https://www.ewtn.com/library/COUNCILS/V1.htm#4|archive-date=2006-02-07}}</ref>

<ref name="bookofconcord.org">{{Cite web |title=The Three Ecumenical Creeds |work=Book of Concord : The Confessions of the Luthernan Church |access-date=9 March 2020 |url=http://bookofconcord.org/creeds.php |archive-date=8 February 2019 |archive-url=https://web.archive.org/web/20190208230430/http://bookofconcord.org/creeds.php |url-status=dead }}</ref>

<ref name="saintandrewsrpcga.org">{{Cite web |title=The Nicene Creed |last=Ashley |first=Greg |work=Saint Andrews Reformed Presbyterian Church |access-date=9 March 2020 |url= http://saintandrewsrpcga.org/nicene.html }}</ref>

<ref name="umc">{{Cite web |url=http://gbgm-umc.org/UMW/BIBLE/ncreed.html |title=United Methodist Hymnal |access-date=22 January 2009 |archive-date=5 February 2012 |archive-url=https://web.archive.org/web/20120205031307/http://gbgm-umc.org/UMW/BIBLE/ncreed.html |url-status=dead }}</ref>

<ref name="victorianweb.org">{{Cite web |title=The 39 Articles of Religion (1562) |work=The Victorian Web |date=December 2001 |access-date=9 March 2020 |url= http://www.victorianweb.org/religion/39articles.html }}</ref>

<ref name="assyrianchurch.org.au">{{Cite web |title=Creed of Nicaea |work=Holy Apostolic Catholic Assyrian Church of the East – Archdiocese of Australia, New Zealand and Lebanon |access-date=9 March 2020 |url=https://www.assyrianchurch.org.au/about-us/faith/creed-of-nicaea/ |archive-date=3 July 2020 |archive-url=https://web.archive.org/web/20200703103338/https://www.assyrianchurch.org.au/about-us/faith/creed-of-nicaea/ |url-status=dead }}</ref>

<ref name="sor.cua.edu">{{cite web|title=The Nicene Creed|website=Syriac Orthodox Resources|date=June 8, 1997|archive-url=https://web.archive.org/web/20120507074543/http://sor.cua.edu/Liturgy/Common/NiceneCreed.html |archive-date=7 May 2012|url= http://sor.cua.edu/Liturgy/Common/NiceneCreed.html}}</ref>

<ref name="EOTC">{{cite web|url=http://www.ninesaintsethiopianorthodoxmonastery.org/id18.html |title=A Brief History of the 1st Universial Council of Nicea|archive-url=https://web.archive.org/web/20110126005944/http://www.ninesaintsethiopianorthodoxmonastery.org/id18.html |archive-date=26 January 2011|website= Nine Saints Ethiopian Orthodox Monastery}}</ref>

<ref name="saintmaryhouston.org">{{Cite web |title=About Us |work=Saint Mary & Archangel Michael Coptic Orthodox Church |access-date=9 March 2020 |url= http://www.saintmaryhouston.org/index.php?q=content/about-us }}</ref>

<ref name="armenianchurchlibrary.com">{{cite web|url=http://www.armenianchurchlibrary.com/files/creed.pdf |title=Nicene Creed|website=armenianchurchlibrary.com|access-date=2020-03-08}}</ref>

<ref name="acrod.org">{{Cite web |url=http://www.acrod.org/sn/sn4a.shtml |title=The Relationship between Prayer and Theology |website =The American Carpatho-Russian Orthodox Diocese of the U.S.A. |archive-url=https://web.archive.org/web/20071011114120/http://www.acrod.org/sn/sn4a.shtml |archive-date=11 October 2007 |access-date=23 February 2013|date=May 9, 2000}}</ref>

<ref name="Neptic Monasticism">{{Cite web |title=The Neptic and Hesychastic Character of Orthodox Athonite Monasticism |last=Georgios |first=Archimandrite |work=greekorthodoxchurch.org |date=n.d. |access-date=9 March 2020 |url= https://www.greekorthodoxchurch.org/neptic_monasticism.html }}</ref>

<ref name="encarta1">{{Cite encyclopedia |title=Church and State in the Byzantine Empire |encyclopedia=Encarta|url=http://encarta.msn.com/encyclopedia_761573998/Church_and_State.html#p3 |archive-url=https://web.archive.org/web/20091029111023/http://encarta.msn.com/encyclopedia_761573998/Church_and_State.html |archive-date=29 October 2009 |url-status=dead}}</ref>

<ref name="encarta2">{{Cite encyclopedia |title=Church and State in Western Europe |encyclopedia=Encarta|url=http://encarta.msn.com/encyclopedia_761573998/Church_and_State.html#p4 |archive-url=https://web.archive.org/web/20091029111023/http://encarta.msn.com/encyclopedia_761573998/Church_and_State.html |archive-date=29 October 2009 |url-status=dead}}</ref>

<ref name="risu.org.ua">{{cite web|archive-url=http://webarchive.loc.gov/all/20050420013442/http://www.risu.org.ua/eng/major.religions/greek.catholic/historical.survey/ |url=http://www.risu.org.ua/eng/major.religions/greek.catholic/historical.survey/|title=The Ukrainian Greek Catholics: A Historical Survey|website= risu.org.ua|access-date= 2 June 2012|archive-date=2005-04-20}}</ref>

<ref name="mkka">{{Cite web |title=ΕΙΝΑΙ ΔΥΝΑΤΗ Η ΕΝΩΣΗ ΤΩΝ ΕΚΚΛΗΣΙΩΝ |trans-title=Is Union of Churches Possible? |author=Metropolitan of Kalavryta and Aigialia Ambrosio |work=mkka.blogspot.com |date=20 November 2008 |access-date=9 March 2020 |url= http://mkka.blogspot.com/2008/11/blog-post_20.html }}</ref>

<ref name="Neuro">{{Cite web |title=The Cure of the Neurobiological Sickness of Religion |last=Romanide |first=John S. |date=n.d. |at=The Council Of Orange 529 Condemned Augustine's Interpretation of Romans 5:12 |access-date=9 March 2020 |url= http://romanity.org/htm/rom.02.en.the_cure_of_the_neurobiological_sickness_of_rel.03.htm#s31 }}</ref>

}}

===Sources===
{{sfn whitelist |CITEREFNicol1993 }}
{{refbegin|30em|indent=yes}}
* {{Cite book |url=http://www.myriobiblos.gr/texts/english/milton1_21.html |title=Aspects of the Mind of Byzantium (Political Theory, Theology, and Ecclesiastical Relations with the See of Rome) |last=Anastos |first=Milton V |publisher=Ashgate Publications |year=2001 |isbn=0-86078-840-7 |series=Variorum Collected Studies }}
* {{Cite journal |year=2001 |journal=Eastern Churches Journal |publisher=Society of Saint John Chrysostom |volume=8 |pages=147– |number=1–2|title=Chronicle of the Eastern Churches|author=Anon.}}
* {{cite book|last=Ayer|first=Joseph Cullen|title=A source book for ancient church history...|url=https://books.google.com/books?id=fM9y0Db-88wC&pg=PT315|year=1941|publisher=Scribner}}
* {{cite journal|last=Azkoul|first=Michael|title=What are the differences between Orthodoxy and Roman Catholicism|journal=The Orthodox Christian Witness|volume=27|issue=48|date=1994|url=http://www.ocf.org/OrthodoxPage/reading/ortho_cath.html|access-date=12 February 2009|archive-date=3 June 2004|archive-url=https://web.archive.org/web/20040603064944/http://www.ocf.org/OrthodoxPage/reading/ortho_cath.html|url-status=dead}}
* {{cite book|last1=Baker|first1=Robert Andrew|last2=Landers|first2=John M.|title=A Summary of Christian History|url=https://books.google.com/books?id=MQvCL1STfaAC&pg=PA110|year=2005|publisher=B&H|isbn=978-0-8054-3288-6}}
* {{cite book|last=Bayer|first=Axel|title=Spaltung der Christenheit: das sogenannte Morgenländische Schisma von 1054|url=https://books.google.com/books?id=LYD7XoGwafAC&pg=PA80|year=2004|publisher=Böhlau|language=de|isbn=978-3-412-14204-9|trans-title=Christianity split : the so-called Oriental Schism of 1054}}
* {{cite book|last1=Becchio|first1=Bruno|last2=Schadé|first2=Johannes P.|title=Encyclopedia of World Religions|url=https://books.google.com/books?id=XRkfKdho-5cC&pg=PT805|year=2006|publisher=Foreign Media Group|isbn=978-1-60136-000-7}}
* {{Citation |last=Beck |first=Hans-Georg |title=Byzantinisches Lesebuch |year=1982 |place=München |language=de}}
* {{cite book|last1=Bihlmeyer|first1=Karl|last2=Tüchle|first2=Hermann|title=Church History: The Middle Ages|url=https://books.google.com/books?id=JqgNAQAAMAAJ|year=1967|publisher=Newman Press}}
* {{cite book|last=Bindley|first=Thomas Herbert|title=The Oecumenical Documents of the Faith|url=https://books.google.com/books?id=3lAOAAAAQAAJ&pg=PA78|year=1980|publisher=Greenwood Press|isbn=978-0-313-22197-2}}
* {{cite book|last=Binns|first=John|title=An Introduction to the Christian Orthodox Churches|url=https://books.google.com/books?id=MOA5vfSl3dwC&pg=PA144|year=2002|publisher=University Press|location=Cambridge|isbn=978-0-521-66738-8}}
* {{cite book|last=Bradford|first=Ernle|title=The Great Betrayal: The Great Siege of Constantinople|url=https://books.google.com/books?id=qkS916lwXScC&pg=PT3+|date=2013|publisher=E-Reads|isbn=978-1-61756-800-8}}{{Dead link|date=July 2023 |bot=InternetArchiveBot |fix-attempted=yes }}
* {{Cite web |title=The Confession of Dositheus (Eastern Orthodox) |last=Bratcher |first=Dennis |work=crivoice.org |date=2018 |access-date=9 March 2020 |url=http://www.crivoice.org/creeddositheus.html }}
* {{cite book|last=Brujić|first=Dragan|title=Vodič kroz svet Vizantije: od Konstantina do pada Carigrada|url=https://books.google.com/books?id=bpZsNgAACAAJ|year=2004|publisher=Dina|location=Beograd|language=bs|isbn=978-86-85275-02-9|trans-title=A guide to the world of Byzantium: from Constantine to the fall of Constantinople}}
* {{cite book|last=Bunson|first=Matthew|title=OSV's Encyclopedia of Catholic History|url=https://books.google.com/books?id=dWpO1--eMrYC&pg=PA24|year=2004|publisher=Our Sunday Visitor|isbn=978-1-59276-026-8}}{{Dead link|date=July 2023 |bot=InternetArchiveBot |fix-attempted=yes }}
* {{cite book|last=Bunson|first=Matthew|title=Encyclopedia of the Roman Empire|url=https://books.google.com/books?id=T5tic2VunRoC&pg=PA115|date=2014|publisher=Infobase|isbn=978-1-4381-1027-1}}
* {{cite book|last=Bury|first=John Bagnell|author-link=John Bagnell Bury|title=The Cambridge Medieval History|url=https://archive.org/details/in.ernet.dli.2015.70261/page/n305/mode/2up|volume=IV|year=1923|publisher=University Press|location=Cambridge}}
* {{cite book|last=Campbell|first=Ted|title=Christian Confessions: A Historical Introduction|url=https://books.google.com/books?id=p2mUxxxGt_sC|date=1996|publisher=Westminster John Knox Press|isbn=978-0-664-25650-0}}
* {{cite book|last=Carlton|first=Clark|title=The Truth: What Every Roman Catholic Should Know about the Orthodox Church|url=https://books.google.com/books?id=oA53PQAACAAJ|year=2007|publisher=Regina Orthodox Press|isbn=978-0-9649141-8-6}}
* {{Cite web |title=Principles and Norms on Ecumenism |last1=Cassidy |first1=Edward Idris Cardinal |last2=Duprey |first2=Pierre |work=vatican.va |date=25 March 1993 |access-date=9 March 2020 |url=https://www.vatican.va/roman_curia/pontifical_councils/chrstuni/general-docs/rc_pc_chrstuni_doc_19930325_directory_en.html }}
* {{cite book|title=Catechism of the Catholic Church|author=Catholic Church|date=1994|publisher=Liguori|url=https://archive.org/details/catechismofcatho00ligu/page/102/mode/2up/|isbn=978-1884660016}}
* {{Cite web |url=http://www.goarch.org/en/ourfaith/articles/article8523.asp |title=Papal primacy |first=Emmanuel |last=Clapsis |publisher=Greek Orthodox Archdiocese of America |archive-url=https://web.archive.org/web/20080617082301/http://www.goarch.org/en/ourfaith/articles/article8523.asp <!-- Bot retrieved archive --> |archive-date=17 June 2008 |access-date=16 October 2008 |date=2005 }}
* {{cite book|last=Cleenewerck|first=Laurent|title=His Broken Body: Understanding and Healing the Schism Between the Roman Catholic and Eastern Orthodox Churches|url=https://books.google.com/books?id=oeKOUb6OcG4C&pg=PA156|year=2007|publisher=Euclid University Press|isbn=978-0-615-18361-9}}{{Self-published source|date=March 2020}}
* {{cite book|last=Cloud|first=Randall R.|title=Aristotle's Journey to Europe: A Synthetic History of the Role Played by the Islamic Empire in the Transmission of Western Educational Philosophy Sources from the Fall of Rome Through the Medieval Period|url=https://books.google.com/books?id=FG5MnQEACAAJ|year=2009|publisher=University Microfilms}}
* {{cite EB1911 |wstitle=Chalcedon, Council of |volume=5 |page=803 |first=Theodore Freylinghuysen |last=Collier}}
* {{cite book|last=Christiansen|first=Eric|title=The Northern Crusades|url=https://archive.org/details/northerncrusades00eric/page/287|year=1997|publisher=Penguin|isbn=978-0-14-026653-5}}
* {{cite book|last1=Christensen|first1=Michael J.|last2=Wittung|first2=Jeffery A.|title=Partakers of the Divine Nature: The History and Development of Deificiation in the Christian Traditions|url=https://books.google.com/books?id=DgtUoMqm594C&pg=PA244|year=2007|publisher=Fairleigh Dickinson Univ Press|isbn=978-0-8386-4111-8}}
* {{cite book|last1=Cross|first1=Frank Leslie|last2=Livingstone|first2=Elizabeth A.|title=The Oxford Dictionary of the Christian Church|chapter-url=https://books.google.com/books?id=fUqcAQAAQBAJ&pg=PA706|year=2005|publisher=University Press|location=Oxford|isbn=978-0-19-280290-3|chapter=Great Schism}}
* {{cite book|last=D'Agostino|first=Michele Giuseppe|title=Il primato della sede di Roma in Leone IX (1049-1054): studio dei testi latini nella controversia greco-romana nel periodo pregregoriano|url=https://books.google.com/books?id=jkrZAAAAMAAJ|year=2008|publisher=San Paolo|isbn=978-88-215-6062-0|chapter=it|trans-title=The primacy of the Roman see in Leo IX (1049–54). Study of the Latin texts in the Greek-Roman controversy in the pre-Gregorian period|oclc=470997792}}
* {{cite book|last=Dawson|first=Christopher|title=The Formation of Christendom|url=https://books.google.com/books?id=wS78LsGaZpkC&pg=PA140|year=2008|publisher=Ignatius Press|isbn=978-1-58617-239-8}}
* {{Cite news |url=https://mospat.ru/ru/2010/02/16/news13315/ |date=16 February 2010 |publisher=The official web site of the Moscow Patriarchate |language=ru |script-title=ru:Современное состояние отношений между Русской Православной и Римско-Католической Церквами: официальный взгляд, Алексей Дикарев |first=Alexey Viktorovich |last=Dikarev |trans-title=The current state of relations between the Russian Orthodox and the Roman Catholic Churches: official view }}
* {{cite book|last1=Doyle|first1=Dennis Michael|last2=Furry|first2=Timothy J.|last3=Bazzell|first3=Pascal D.|title=Ecclesiology and Exclusion: Boundaries of Being and Belonging in Postmodern Times|url=https://books.google.com/books?id=K_lvImfHGhYC&pg=PA311|year=2012|publisher=Orbis|isbn=978-1-60833-217-5}}
* {{cite book|last=Dragani|first=Anthony|title=Adrian Fortescue and the Eastern Christian Churches|url=https://books.google.com/books?id=sU1WvgAACAAJ&pg=PA44|year=2005|publisher=Gorgias|isbn=978-1-59333-345-4}}
* {{cite book|last=Dvorník|first=František|title=The Study of Church History and Christian Reunion ... Reprinted from The Eastern Churches Quarterly, Etc|url=https://books.google.com/books?id=XqQLMwEACAAJ|year=1945|publisher=Exeter}}
* {{cite book|last=Dwyer|first=John C.|title=Church History: Twenty Centuries of Catholic Christianity|url=https://books.google.com/books?id=FKvo3szVq_sC|year=1998|publisher=Paulist Press|isbn=978-0-8091-3830-2}}
* {{cite book|last=Ekonomou|first=Andrew J.|title=Byzantine Rome and the Greek Popes: Eastern Influences on Rome and the Papacy from Gregory the Great to Zacharias, A.D. 590-752|url=https://books.google.com/books?id=zomZk6DbFTIC&pg=PA222|year=2007|publisher=Lexington Books|isbn=978-0-7391-1977-8}}
* {{cite book|last=Ferencz|first=Nicholas|title=American Orthodoxy and Parish Congregationalism|url=https://books.google.com/books?id=Uh4VnseTNZkC&pg=PA21|year=2006|publisher=Gorgias Press|isbn=978-1-59333-195-5}}{{Dead link|date=July 2023 |bot=InternetArchiveBot |fix-attempted=yes }}
* {{cite book|last=Fortescue|first=Adrian|author-link=Adrian Fortescue|title=The Orthodox Eastern Church|url=https://archive.org/details/orthodoxeasternc00fort/page/146/mode/2up|year=1907|publisher=Catholic Truth Society}}
* {{cite CE1913|last=Fortescue|first=Adrian|wstitle=The Eastern Schism|volume=13}}
* {{cite news|title=Report on Catholic-Orthodox Relations|first=Eleuterio F.|last=Fortino|newspaper=L'Osservatore Romano|date=9 February 2005|archive-url=https://web.archive.org/web/20160304055958/https://www.ewtn.com/library/Theology/CATORT04.HTM|archive-date=4 March 2016|url=https://www.ewtn.com/library/Theology/CATORT04.HTM}}
* {{cite book|last=Fossier|first=Robert|title=The Cambridge Illustrated History of the Middle Ages|url=https://archive.org/details/cambridgeillustr00robe|url-access=registration|year=1986|publisher=Cambridge University Press|isbn=978-0-521-26645-1}}
* {{cite book|last1=Gaillardetz|first1=Richard|last2=Wilson|first2=Kenneth|title=Readings in Church Authority: Gifts and Challenges for Contemporary Catholicism|url=https://books.google.com/books?id=aezGH7vcWMEC&pg=PA211|year=2003|publisher=Ashgate|isbn=978-0-7546-0530-0}}
* {{cite book|last=Gaillardetz|first=Richard R.|title=The Church in the Making: Lumen Gentium, Christus Dominus, Orientalium Ecclesiarum|url=https://books.google.com/books?id=_iFSYQskQPUC&pg=PA46|year=2006|publisher=Paulist Press|isbn=978-0-8091-4276-7}}
* {{cite web |url=http://www.ctlibrary.com/ch/1997/issue54/54h010.html |first=Mark |last=Galli |title=The Great Divorce |archive-url=https://web.archive.org/web/20110914171457/http://www.ctlibrary.com/ch/1997/issue54/54h010.html |archive-date=14 September 2011 |website=Ctlibrary.com |date=1 April 1997 |access-date=2 June 2012 }}
* {{cite book|last=Garuti|first=Adriano|title=The Primacy of the Bishop of Rome and the Ecumenical Dialogue|url=https://archive.org/details/primacyofbishopo0000garu|url-access=registration|page=[https://archive.org/details/primacyofbishopo0000garu/page/66 66]|year=2004|publisher=Ignatius Press|isbn=978-0-89870-879-0}}
* {{cite book|last=Geanakoplos|first=Deno John|title=Constantinople and the West: Essays on the Late Byzantine (Palaeologan) and Italian Renaissances and the Byzantine and Roman Churches|url=https://books.google.com/books?id=_6PYWPWWhrUC&pg=PA172|year=1989|publisher=Univ of Wisconsin Press|isbn=978-0-299-11884-6}}
* {{cite book|last=Giannaras|first=Chrēstos|title=The Freedom of Morality|url=https://books.google.com/books?id=x68bAQAAMAAJ|year=1984|publisher=St. Vladimir's Seminary Press|isbn=978-0-88141-028-0}}
* {{cite book|last=Haight|first=Roger|author-link=Roger Haight|title=Christian Community in History|url=https://books.google.com/books?id=EDzSaqXK-aEC&pg=PA289|volume=1: Historical Ecclesiology|year=2004|publisher=A&C Black|isbn=978-0-8264-1630-8}}
* {{cite book|last=Harris|first=Jonathan|title=Byzantium and the Crusades|url=https://books.google.com/books?id=PXizk1RZ88wC|date=2006|publisher=A&C Black|isbn=978-1-85285-501-7}}
* {{cite book|last1=Hartmann|first1=Wilfried|last2=Pennington|first2=Kenneth|title=The History of Byzantine and Eastern Canon Law to 1500|url=https://books.google.com/books?id=BwnCVYHf5VAC&pg=PA63|date=2012|publisher=CUA Press|isbn=978-0-8132-1679-9}}
* {{cite book |last=Hergenröther |first=J |title=Monumenta Graeca ad Photium eiusque historiam pertinentiam |year=1869 |place=Regensburg |language=la}}
* {{cite book|last=Herrin|first=Judith|title=Margins and Metropolis: Authority Across the Byzantine Empire|url=https://books.google.com/books?id=iKlR4xyOmKUC&pg=PA11|year=2013|publisher=Princeton University Press|isbn=978-0-691-15301-8}}
* {{Cite web |title=Roman Presidency and Christian Unity in our Time |last=Hopko |first=Thomas |work=orthodoxytoday.org |date=25 September 2005 |access-date=7 March 2020 |url=http://www.orthodoxytoday.org/articles6/HopkoPope.php }}
* {{cite book|last=Howard|first=Jonathan|title=The Crusades: A History of One of the Most Epic Military Campaigns of All Time|url=https://books.google.com/books?id=YWEUg5pMqJYC&pg=PT21|year=2011|publisher=BookCaps Study Guides|isbn=978-1-61042-804-0}}
* {{cite web|url= http://www.stmaryorthodoxchurch.org/orthodoxy/articles/ancestral_versus_original_sin|title= Ancestral Versus Original Sin: An Overview with Implications for Psychotherapy|first= Antony|last= Hughes|website= St. Mary Antiochian Orthodox Church|location= Cambridge, Massachusetts|date= n.d.}}
* {{cite book|last=Hughes|first=Philip|title=History of the Church|url=https://books.google.com/books?id=L2nvpmOLdLwC&pg=PA29|volume=3: The Revolt Against The Church: Aquinas To Luther|year=1979|publisher=A&C Black|isbn=978-0-7220-7983-6}}
* {{cite book|last=Hussey|first=Joan Mervyn|title=The Cambridge Medieval History|url=https://books.google.com/books?id=Zus8AAAAIAAJ&pg=PA177|volume=8|year=1967|publisher=University Press|location=Cambridge|id=GGKEY:W8456N5J140}}
* {{cite book|author=Ignatius of Antioch|editor=William Wake|title=Genuine Epistles of the Apostolic Fathers|chapter-url=https://books.google.com/books?id=KncuAQAAIAAJ&pg=PA116|year=1846|publisher=Davis|chapter=The Epistle of Ignatius to the Smyrnaeans}}
* {{cite book|last1=Jeffreys|first1=Elizabeth|last2=Haldon|first2=John F.|last3=Cormack|first3=Robin|title=The Oxford Handbook of Byzantine Studies|url=https://books.google.com/books?id=Pnkxofhi4mQC&pg=PA596|year=2008|publisher=Oxford University Press|isbn=978-0-19-925246-6}}
* {{cite web|url=https://www.vatican.va/holy_father/john_paul_ii/encyclicals/documents/hf_jp-ii_enc_25051995_ut-unum-sint_en.htmlEncyciclical|title=Ut unum sint|trans-title=In order to be one!|author=John Paul II|author-link=John Paul II|date=25 May 1995|access-date=4 March 2020|at=54}}
* {{Cite web |title=Common Declaration signed by the Holy Father and the Ecumenical Patriarch His Holiness Bartholomew I |author=John Paul II |work=vatican.va |date=29 June 2004 |access-date=9 March 2020 |url=https://www.vatican.va/content/john-paul-ii/en/speeches/2004/july/documents/hf_jp-ii_spe_20040701_jp-ii-bartholomew-i.html }}
* {{cite encyclopedia|first=Walter Emil|last=Kaegi|title=Leo III &#124; Byzantine emperor|chapter=Leo III|encyclopedia=Encyclopædia Britannica|date=14 June 2019|chapter-url=https://www.britannica.com/biography/Leo-III|access-date=7 March 2020}}
* {{cite book|last1=Kelly|first1=John Norman Davidson|last2=Walsh|first2=Michael J.|title=The Oxford dictionary of popes|url=https://books.google.com/books?id=ExYOAQAAMAAJ|year=2005|publisher=Oxford University Press|isbn=978-0-19-861433-3|doi=10.1093/acref/9780199295814.001.0001}}
* {{cite book|last=Kelly|first=J.N.D.|title=Early Christian Creeds|url=https://books.google.com/books?id=Titk-TEYqD4C&pg=PA296|year=2006|publisher=A&C Black|isbn=978-0-8264-9216-6}}
* {{cite book|last=Kidd|first=B.J.|title=Churches Of Eastern Christendom|url=https://books.google.com/books?id=tc5FAAAAQBAJ&pg=PA208|year=2013|publisher=Routledge|isbn=978-1-136-21278-9}}
* {{cite book|last=King|first=Archdale|title=The Rites of Eastern Christendom|url=https://books.google.com/books?id=SJjZAAAAMAAJ|volume=1|year=2006|publisher=Gorgias Press|isbn=978-1-59333-390-4}}
* {{cite book|last=Kling|first=David W.|title=The Bible in History: How the Texts Have Shaped the Times|url=https://books.google.com/books?id=61g19QTJk5UC&pg=PA61|year=2004|publisher=University Press|location=Oxford|isbn=978-0-19-988096-6}}
* {{cite encyclopedia|first1=Michael David|last1=Knowles|first2=Lawrence|last2=Cunningham|display-authors=etal|title=Roman Catholicism|encyclopedia=Encyclopædia Britannica|date=29 November 2019|access-date=8 March 2020|url=https://www.britannica.com/topic/Roman-Catholicism}}
* {{Cite web |title=Orthodox Catholic Interpretation of Roman Catholic Claims of Papal Primacy and Jurisdiction |last=Krehel |first=Damian |work=Orthodox Research Institute |date=2017 |access-date=8 March 2020 |url=http://www.orthodoxresearchinstitute.org/articles/dogmatics/krehel_orthodox_catholic_faith.htm#_ednref21 }}
* {{cite book|last=Leith|first=John H.|title=Creeds of the Churches: A Reader in Christian Doctrine, from the Bible to the Present|url=https://books.google.com/books?id=saFgJRjaPwcC|year=1982|publisher=Westminster John Knox Press|isbn=978-0-8042-0526-9}}
* {{Citation |last=Lembke |first=Martin |title=Meetings with the World's Religions |date=Spring 2010 |type=lecture |place=Lund University |publisher=Centre for Theology and Religious Studies}}
* {{cite book|last=Lossky|first=Nicholas O.|title=History of Russian Philosophy|url=https://books.google.com/books?id=KqunJwAACAAJ|year=1969|publisher=International Universities Press|isbn=978-0-8236-8074-0}}
* {{cite book|last=Lossky|first=Vladimir|title=The Mystical Theology of the Eastern Church|url=https://books.google.com/books?id=dxqvWwPSCSwC|year=1976|publisher=St Vladimir's Seminary Press|isbn=978-0-913836-31-6}}
* {{cite book|last=Louth|first=Andrew|title=Greek East and Latin West: The Church, AD 681–1071|url=https://books.google.com/books?id=WlpPjOlVzQwC|year=2007|publisher=St Vladimir's Seminary Press|isbn=978-0-88141-320-5}}
* {{cite book|last=Macquarrie|first=John|title=Mary for All Christians|url=https://books.google.com/books?id=Tk3GcuRO43MC&pg=PA75|year=2001|publisher=A&C Black|isbn=978-0-567-08751-5}}
* {{cite book|last=Makrides|first=Vasilios|title=Hellenic Temples and Christian Churches: A Concise History of the Religious Cultures of Greece from Antiquity to the Present|url=https://books.google.com/books?id=kKOY5NsekfkC&pg=PA68|year=2009|publisher=NYU Press|isbn=978-0-8147-9568-2}}
* {{cite book|last=McBrien|first=Richard P.|title=The HarperCollins Encyclopedia of Catholicism|url=https://archive.org/details/harpercollinsenc00mcbr|url-access=registration|page=[https://archive.org/details/harpercollinsenc00mcbr/page/529 529]|year=1995|publisher=HarperCollins|isbn=978-0-06-065338-5}}
* {{cite book|last=McGuckin|first=John|title=St. Cyril of Alexandria: The Christological Controversy: Its History, Theology, and Texts|url=https://books.google.com/books?id=Q-p5DwAAQBAJ&pg=PA173|date=1994|publisher=BRILL|isbn=978-90-04-31290-6}}
* {{Cite book |url=https://books.google.com/books?id=KLIFfmipXcoC&pg=PA32 |title=The Orthodox Church: An Introduction to its History, Doctrine, and Spiritual Culture |last=McGuckin |first=John Anthony |date=2010 |publisher=John Wiley & Sons |isbn=978-1-4443-3731-0 }}
* {{cite book|last=McKim|first=Donald K.|title=Westminster Dictionary of Theological Terms|chapter-url=https://books.google.com/books?id=UJ9PYdzKf90C&pg=PA35|year=1996|publisher=Westminster John Knox Press|isbn=978-0-664-25511-4|chapter=caesaropapism}}
* {{cite book|last=McPartlan|first=Paul|title=Sacrament of Salvation: An Introduction to Eucharistic Ecclesiology|url=https://books.google.com/books?id=tSiha9BMxEQC&pg=PR15+|year=1995|publisher=A&C Black|isbn=978-0-567-29299-5}}
* {{Cite web |url=http://www.aoiusa.org/canon-28-and-eastern-papalism-cause-or-effect/ |title=Canon 28 and Eastern Papalism: Cause or Effect? |first=George C. |last=Michalopulos |date=11 September 2009 |publisher=Aoiusa.org |url-status=dead |archive-url=https://web.archive.org/web/20130110112941/http://www.aoiusa.org/canon-28-and-eastern-papalism-cause-or-effect/ |archive-date=10 January 2013 |access-date=23 February 2013 }}
* {{cite book|url=https://archive.org/stream/patrologiaecurs86unkngoog#page/n375/mode/2up|editor-last=Migne|editor-first=J-P|title=Patrologiae cursus completus: sive biblioteca universalis, integra uniformis, commoda, oeconomica...|location=Paris|publisher=Garnier|date=1882}}
* {{cite book|last=Millet|first=Robert L.|title=By what Authority?: The Vital Question of Religious Authority in Christianity|url=https://books.google.com/books?id=bV4RUW6Unn4C&pg=PA43|year=2010|publisher=Mercer University Press|isbn=978-0-88146-201-2}}
* {{cite book|last=Mouravieff|first=Andreĭ Nikolaevich|title=A History of the Church of Russia|url=https://archive.org/details/historyofchurcho00mouriala|page=[https://archive.org/details/historyofchurcho00mouriala/page/165 165]|year=1842|publisher=John Henry Parker}}
* {{cite book|last=Murray|first=Stuart|title=The Library: An Illustrated History|url=https://books.google.com/books?id=FCP9kHegLOcC&pg=PA53|year=2009|publisher=Skyhorse|isbn=978-1-60239-706-4}}
* {{cite book|last=Nicol|first=Donald M.|editor-first1=G.J.|editor-last1=Cuming|editor-first2=Derek|editor-last2=Baker|title=Councils and Assemblies: Papers Read at the Eighth Summer Meeting and the Ninth Winter Meeting of the Ecclesiastical History Society|chapter-url=https://books.google.com/books?id=QfM8AAAAIAAJ&pg=PA136|year=1971|publisher=University Press|location=Cambridge|isbn=978-0-521-08038-5|chapter=The Byzantine Reaction to the Second Council of Lyons, 1274}}
* {{Byzantium and Venice: A Study in Diplomatic and Cultural Relations}}
* {{The Last Centuries of Byzantium, 1261-1453}}
* {{The Byzantine Lady: Ten Portraits, 1250–1500}}
* {{cite book |last1=Nicol |first1=Donald M. |title=The Byzantine Lady: Ten Portraits, 1250–1500 |date=1996 |publisher=Cambridge University Press |isbn=978-0-521-57623-9 |url=https://books.google.com/books?id=PThFM3RS3h0C&pg=PA38 |language=en }}
* {{cite journal|url=http://www.christendom-awake.org/pages/anichols/orthodox.html|first=Aidan|last=Nichols|title=A Catholic View of Orthodoxy|journal=New Blackfriars|volume=77|issue=905|pages=264–275|date=June 1996|jstor=43249880|doi=10.1111/j.1741-2005.1996.tb01555.x|url-access=subscription}}
* {{Cite book |url=https://books.google.com/books?id=Hje62q52XNsC |title=Rome and the Eastern Churches: a study in schism |last=Nichols |first=Aidan |publisher=Ignatius Press |year=2010 |isbn=978-1-58617282-4 }}
* {{Cite web |title=His Beatitude Sviatoslav disappointed in Joint Declaration; laments Vatican's "weaker team" |last=Olson |first=Carl E. |work=catholicworldreport.com |date=14 February 2016 |access-date=9 March 2020 |url=https://www.catholicworldreport.com/2016/02/14/his-beatitude-sviatoslav-disappointed-in-joint-declaration-laments-vaticans-weaker-team/ }}
* {{cite CE1913|last=Ott|first=Michael|wstitle=Pope Martin IV|volume=9}}
* {{Citation |first=Sidney |last=Palatianos |title=The Photian Schism leading to the Great Schism of 1054 |url=http://loki.stockton.edu/~papadema/Syndey_Palatianos.pdf |archive-url=https://web.archive.org/web/20110720051937/http://loki.stockton.edu/~papadema/Syndey_Palatianos.pdf |publisher=Stockton |access-date=9 July 2010 |archive-date=20 July 2011 |url-status=dead |date=n.d. }}
* {{cite book|last1=Papadakis|first1=Aristeides|last2=Meyendorff|first2=John|title=The Christian East and the Rise of the Papacy: The Church 1071–1453 A.D.|url=https://books.google.com/books?id=xHvYAAAAMAAJ|year=1994|publisher=St. Vladimir's Seminary Press|isbn=978-0-88141-058-7}}
* {{Cite web |title=Conclusion of the II Vatican Council: Joint Catholic-Orthodox declaration, approved by Pope Paul VI and Ecumenical Patriarch Athenagoras I of Constantinople |author=Paul VI |author-link=Paul VI |work=vatican.va |date=7 December 1965 |access-date=9 March 2020 |url=https://www.vatican.va/content/paul-vi/en/speeches/1965/documents/hf_p-vi_spe_19651207_common-declaration.html }}
* {{cite book|last=Pelikan|first=Jaroslav|author-link=Jaroslav Pelikan|title=The Christian Tradition: A History of the Development of Doctrine|url=https://books.google.com/books?id=Lr3ebI4iiwcC&pg=PA170|volume=2: The Spirit of Eastern Christendom (600–1700)|year=1971|publisher=University of Chicago Press|isbn=978-0-226-65373-0}}
* {{cite book|last=Penn|first=Imma|title=Dogma Evolution & Papal Fallacies|url=https://books.google.com/books?id=9MBnbFg-jJgC&pg=PA134|year=2007|publisher=AuthorHouse|isbn=978-1-4520-5994-5}}
* {{cite book|last=Phan|first=Peter C.|title=The Gift of the Church: A Textbook on Ecclesiology in Honor of Patrick Granfield, O.S.B.|url=https://books.google.com/books?id=2knW3bIxIYgC&pg=PA37|year=2000|publisher=Liturgical Press|isbn=978-0-8146-5931-1}}
* {{cite book|last=Pomazansky|first=Michael |title=Orthodox Dogmatic Theology: A Concise Exposition|year=1984|publisher=Saint Herman of Alaska Brotherhood|isbn=978-0-938635-69-7}}
* {{cite book|last=Pospielovsky|first=Dimitry|title=The Orthodox Church in the History of Russia|url=https://books.google.com/books?id=2cP0wc_E6yEC&pg=PA96|date=1998|publisher=St. Vladimir's Seminary Press|isbn=978-0-88141-179-9}}
* {{cite book|last=Previté-Orton|first=C. W.|author-link=Charles William Previté-Orton|title=The Shorter Cambridge Medieval History|url=https://books.google.com/books?id=RXU5AAAAIAAJ&pg=PA276|volume=1: The Later Roman Empire to the Twelfth Century|year=1975|publisher=University Press|location=Cambridge|isbn=978-0-521-09976-9}}
* {{Cite book |url=https://books.google.com/books?id=pEaxgHlMQbcC&pg=PA162 |title=The Ratzinger Reader: Mapping a Theological Journey |last1=Ratzinger |first1=Joseph |last2=Boeve |first2=Lieven |last3=Mannion |first3=Gerard |date=2010 |publisher=Continuum International |isbn=978-0-567-03214-0 }}
* {{cite book|last1=Rausch|first1=Thomas P.|last2=Clifford|first2=Catherine E.|title=Catholicism in the Third Millennium|url=https://books.google.com/books?id=o4jG7X95mMQC&pg=PA20|year=2003|publisher=Liturgical Press|isbn=978-0-8146-5899-4}}
* {{cite book|last=Rautman|first=Marcus Louis|title=Daily Life in the Byzantine Empire|url=https://books.google.com/books?id=hs3iEyVRHKsC&pg=PR17|year=2006|publisher=Greenwood|isbn=978-0-313-32437-6}}
* {{cite book|first=J. H.|last=Robinson|title=Readings in European History|location=Boston|publisher=Ginn|date=1905|url=https://sourcebooks.fordham.edu/source/gelasius1.asp}}
* {{cite book|last=Romanides|first=John S.|editor=Hannu T. Kamppuri|title=Xenia Oecumenica in Honorem Joannis Metropolitae Helsingiensis Sexagenarii|url=https://books.google.com/books?id=XQssAAAAMAAJ|year=1983|publisher=Missiologian ja Ekumeniikan Seura|chapter=Jesus Christ – The Life of the World|isbn=978-9519520643}}
* {{cite book|last1=Rōmanidēs|first1=Iōannēs S.|author-link=John Romanides|last2=Gabriel|first2=George S.|title=The Ancestral Sin|url=https://books.google.com/books?id=TttVAAAAYAAJ|year=2002|publisher=Zephyr|isbn=978-0-9707303-1-2|oclc=50239361}}
* {{Cite book |chapter=Ch. 1 What is the Human Nous? |title=Patristic Theology – The University Lectures of Father John Romanides |location=Thessaloniki |publisher=Uncut Mountain Press |date=2008 |last=Romanides |first=John |via=orthodoxinfo.com |url=http://orthodoxinfo.com/phronema/patristic-theology-romanides-chapter-1-what-is-the-human-nous.aspx }}
* {{cite book|last=Runciman|first=Steven|title=The Eastern Schism: A Study of the Papacy and the Eastern Churches During the XIth and XIIth Centuries|url=https://books.google.com/books?id=8NUNAQAAIAAJ|year=1955|publisher=Clarendon Press|location=Oxford|isbn=978-0198264170|author-link=Steven Runciman}}
* {{cite book|last=Runciman|first=Steven|title=The Byzantine Theocracy: The Weil Lectures, Cincinnati|url=https://books.google.com/books?id=YQYe7VGlym8C|date=2004|publisher=Cambridge University Press|isbn=978-0-521-54591-4}}
* {{cite book|first=Philip|last=Schaff|url=https://archive.org/details/creedsofchristen01scha/page/24/mode/2up|date=1877|title=The creeds of Christendom|location=New York|publisher=Harper}}
* {{cite book|first=Philip|last=Schaff|url=https://archive.org/details/historyofchristi191304scha/page/320/mode/2up/search/During+the+Crusades|date=1913|title=History of the Christian church|volume=IV: Mediaeval Christianity from Gregory I to Gregory VII, A.D. 590–1073|location=New York|publisher=Scribner's Sons}}
* {{cite book|first=Philip|last=Schaff|url=https://www.ccel.org/ccel/schaff/hcc6.iii.iii.vii.html|date=1910a|title=History of the Christian church|volume=VI. The Middle Ages from Boniface VIII, 1294 to the Protestant Reformation, 1517|location=New York|publisher=Scribner's Sons}}
* {{cite book|first=Philip|last=Schaff|url=https://archive.org/details/historyofchristi52scha/page/179/mode/2up|date=1910|title=History of the Christian church|volume=V Part 2: From Boniface VIII, 1294 to the Protestant Reformation, 1517|location=New York|publisher=Scribner's Sons}}
* {{cite book|editor-first=Philip|editor-last=Schaff|url=https://archive.org/details/selectlibraryofn01scha/page/240/mode/2up|date=1904|title=A Select library of Nicene and post-Nicene fathers of the Christian church. Second series|volume=I : Eusebius Pamphilius: Church History, Life of Constantine, Oration in Praise of Constantine|location=New York|publisher=Scribner's Sons}}
* {{cite book|editor-first=Philip|editor-last=Schaff|url=https://archive.org/details/selectlibraryofn14scha/page/286/mode/2up|date=1916|title=A Select library of Nicene and post-Nicene fathers of the Christian church. Second series|volume=XIV : The Seven Ecumenical Councils|location=New York|publisher=Scribner's Sons}}
* {{cite book|last=Schatz|first=Klaus|title=Der päpstliche Primat: seine Geschichte von den Ursprüngen bis zur Gegenwart|archive-url=https://web.archive.org/web/20121101030052/http://www.sankt-georgen.de/leseraum/schatz2-2.html|chapter-url=http://www.sankt-georgen.de/leseraum/schatz2-2.html|archive-date=1 November 2012|access-date=1 February 2013|year=1990|publisher=Echter|isbn=978-3-429-01274-8|chapter=Zweiter Hauptteil Unterschiedliche Einheitsfunktion In Ost Und West|language=de|trans-title=History of the papal primacy}}
* {{cite book|last1=Setton|first1=Kenneth Meyer|last2=Baldwin|first2=Marshall W.|title=A History of the Crusades|url=https://books.google.com/books?id=RfO1J6hjcdgC&pg=PA210|year=1969|publisher=Univ of Wisconsin Press|isbn=978-0-299-04834-1}}
* {{Cite book|author=Severus|date=1903|url=https://archive.org/details/sixthbookselect01broogoog/page/n8/mode/2up|title=The Sixth Book of the Select Letters of Severus, Patriarch of Antioch|volume=II|editor=E.W. Brooks|publisher=Published for the Textand translation societyby Williams and Norgate}}
* {{cite book|last=Shaw|first=Russell B.|title=Papal Primacy in the Third Millennium|url=https://archive.org/details/papalprimacyinth00shaw|url-access=registration|page=[https://archive.org/details/papalprimacyinth00shaw/page/40 40]|year=2000|publisher=Our Sunday Visitor|isbn=978-0-87973-555-5}}
* {{cite book|last=Sherrard|first=Philip|title=Church, Papacy, and Schism: A Theological Enquiry|url=https://books.google.com/books?id=BtvhAAAACAAJ|year=1996|publisher=Denise Harvey|isbn=978-960-7120-11-3}}
* {{Cite book |url=https://books.google.com/books?id=auT8VbgOe48C |title=The Filioque: History of a Doctrinal Controversy |last=Siecienski |first=Anthony Edward |publisher=Oxford University Press |year=2010 |isbn=978-0195372045 }}
* {{cite book|last=Smith|first=George Adam|title=Atlas of the historical geography of the Holy Land|publisher=Hodder & Stoughton|date=1915|url=https://archive.org/details/ldpd_7032971_000/page/n101/mode/2up}}
* {{cite book|last=Soloviev|first=V. S.|editor=Vladimir Wozniuk|title=Freedom, Faith, and Dogma: Essays by V. S. Soloviev on Christianity and Judaism|url=https://books.google.com/books?id=ftjKBRToMygC&pg=PA14|year=2009|publisher=SUNY Press|isbn=978-0-7914-7536-2}}
* {{cite book|editor-first=Jack Norman|editor-last=Sparks|title=The Orthodox Study Bible, eBook: Ancient Christianity Speaks to Today's World|url=https://books.google.com/books?id=KAh2OOGPsMMC&pg=PA1363|year=2008|publisher=Thomas Nelson|isbn=978-1-4185-7636-3}}
* {{Cite news |title=Obituary: Pope John Paul II |last1=Stanford |first1=Peter |last2=Hebblethwaite |first2=Peter |last3=Hebblethwaite |first3=Margaret |newspaper=The Guardian |date=2 April 2005 |access-date=2 March 2020 |url=https://www.theguardian.com/world/2005/apr/02/guardianobituaries.catholicism }}
* {{cite book|last=Stefoff|first=Rebecca|title=Monarchy|url=https://books.google.com/books?id=3_HhJcQhhoYC&pg=PA62|year=2008|publisher=Marshall Cavendish|isbn=978-0-7614-2630-1}}
* {{Citation |last=Taft |first=Robert F |title=Perceptions and Realities in Orthodox–Catholic Relations Today |url=http://www.fordham.edu/images/theology/orthodoxy/orthodoxy%20in%20america%20taft.pdf |year=2010 |publisher=Fordham |ref=none }}{{dead link|date=February 2016 }}
* {{cite book|last=Thornton|first=Robinson|title=Lives of eminent Russian prelates|chapter-url=https://books.google.com/books?id=xlIBAAAAQAAJ&pg=PA3|year=1854|publisher=Joseph Masters|location=London|chapter=Nikon, sixth Patriarch of Moscow|oclc=721101635}}
* {{cite CE1913|wstitle=God|first=Patrick Joseph |last=Toner}}
* {{cite book|last=Tougher|first=Shaun|title=The Reign of Leo VI (886–912): Politics and People|url=https://books.google.com/books?id=iPquae5A4zIC|year=1997|publisher=Brill|isbn=90-04-10811-4}}
* {{cite book|last=Treadgold|first=Donald W.|title=The West in Russia and China: Russia, 1472–1917|url=https://archive.org/details/westinrussiachin0000trea|url-access=registration|page=[https://archive.org/details/westinrussiachin0000trea/page/2 2]|year=1973|publisher=University Press|location=Cambridge|isbn=978-0-521-09725-3}}
* {{cite book|last1=Trigilio|first1=John|last2=Brighenti|first2=Kenneth|title=Catholicism For Dummies|url=https://books.google.com/books?id=R9V9GsP3FXMC|year=2011|publisher=John Wiley & Sons|isbn=978-1-118-05378-2}}
* {{cite book|last=Ullmann|first=Walter|title=A Short History of the Papacy in the Middle Ages|url=https://books.google.com/books?id=UdB64ytwmaQC&pg=PA64|year=2004|publisher=Taylor & Francis|isbn=978-0-203-34952-6}}
* {{cite book|last=VanVoorst|first=Jenny Fretland|title=The Byzantine Empire|url=https://books.google.com/books?id=RyOoBQiCm88C&pg=PA14|date=2012|publisher=Capstone|isbn=978-0-7565-4565-9}}
* {{cite book|last1=Vauchez|first1=André|last2=Lapidge|first2=Michael|title=Encyclopedia of the Middle Ages|url=https://books.google.com/books?id=om4olQhrE84C&pg=PA1016|year=2000|publisher=Fitzroy Dearborn|isbn=978-1-57958-282-1}}
* {{cite book|last=Vlachos|first=Hierotheos|title=The Illness and Cure of the Soul in the Orthodox Tradition|url=https://books.google.com/books?id=F27IAAAACAAJ|year=1993|publisher=Birth of the Theotokos Monastery Press|isbn=978-960-7070-18-0}}
* {{cite book|last=Vlachos|first=Hierotheos|author-link=Hierotheos Vlachos|title=Orthodox Psychotherapy: (the Science of the Fathers)|archive-url=https://web.archive.org/web/20090225105941/http://www.pelagia.org/htm/b02.en.orthodox_psychotherapy.03.htm#in|archive-date=25 February 2009|url=http://www.pelagia.org/htm/b02.en.orthodox_psychotherapy.03.htm#in|year=1994|publisher=Birth of the Theotokos Monastery|isbn=978-960-7070-27-2|translator=Esther Williams}}
* {{cite book|last=Vlachos|first=Hierotheos|title=Life After Death|url=https://books.google.com/books?id=zyJxAAAAMAAJ|year=1996|publisher=Birth of the Theotokos Monastery|isbn=978-960-7070-34-0}}
* {{cite book|last=Volf|first=Miroslav|author-link=Miroslav Volf|title=After Our Likeness: The Church as the Image of the Trinity|url=https://books.google.com/books?id=J-s7xzugXqkC&pg=PA42|year=1998|publisher=Wm. B. Eerdmans|isbn=978-0-8028-4440-8}}
* {{cite book|last=Volz|first=Carl A.|title=The Medieval Church: From the Dawn of the Middle Ages to the Eve of the Reformation|url=https://books.google.com/books?id=U_g1S4pyyOIC&pg=PT73|date=2011|publisher=Abingdon Press|isbn=978-1-4267-2477-0}}
* {{cite book|last=Walsh|first=Michael J.|title=Pocket Dictionary of Popes|url=https://books.google.com/books?id=vWP_K-lZCB0C&pg=PA107|date=2006|publisher=A&C Black|isbn=978-0-86012-420-7}}
* {{cite book|last=Ware|first=Timothy|title=The Orthodox Church|url=https://archive.org/details/orthodoxchurchac00ware|date=1963|publisher=Penguin|isbn=978-0140205923}}
* {{cite book|last=Ware|first=Timothy|title=The Orthodox Way|url=https://archive.org/details/orthodoxway0000ware|url-access=registration|page=[https://archive.org/details/orthodoxway0000ware/page/77 77]|year=1995|publisher=St Vladimir's Seminary Press|isbn=978-0-913836-58-3}}
* {{cite book|last=Wetterau|first=Bruce|title=World History: A Dictionary of Important People, Places, and Events from Ancient Times to the Present|url=https://archive.org/details/worldhistorydict00wett|url-access=registration|year=1994|publisher=H. Holt|isbn=978-0-8050-2350-3}}
* {{cite book|last=Whitehead|first=K. D.|title=One, Holy, Catholic, and Apostolic: The Early Church was the Catholic Church|url=https://books.google.com/books?id=5V1xelf69XAC&pg=PT244|date=2000|publisher=Ignatius Press|isbn=978-0-89870-802-8}}
* {{cite CE1913|wstitle=General Councils|volume =4 |first=Joseph|last= Wilhelm}}
* {{cite book|last=Williams|first=George L.|title=Papal Genealogy: The Families and Descendants of the Popes|url=https://books.google.com/books?id=-mq7ctwMNdoC&pg=PA37|date=2004|publisher=McFarland|isbn=978-0-7864-2071-1}}
* {{cite book|last=Wolfram|first=Wolfram|title=History of the Goths|url=https://books.google.com/books?id=xsQxcJvaLjAC&pg=PA328|date=1990|publisher=University of California Press|isbn=978-0-520-06983-1}}
* {{cite book|last=Zoghby|first=Elias|title=A Voice from the Byzantine East|url=https://books.google.com/books?id=oYs2AgAACAAJ|year=1992|publisher=Educational Services, Diocese of Newton|isbn=978-1-56125-018-9}}
{{Refend}}

=== Further reading ===
{{Refbegin}}
* Bremer, Thomas [http://ieg-ego.eu/en/threads/models-and-stereotypes/the-west-as-enemy/thomas-bremer-the-west-as-the-archetypal-enemy-in-the-theological-and-philosophical-discourse-of-orthodox-christianity?set_language=en&-C= ''The "West" as the Archetypal Enemy in the Theological and Philosophical Discourse of Orthodox Christianity''], [http://www.ieg-ego.eu/ EGO – European History Online], Mainz: [http://www.ieg-mainz.de/likecms/index.php Institute of European History], 2017, retrieved: March 8, 2021 ([https://d-nb.info/1149294663/34 pdf]).
* Henry Chadwick. ''East and West: The Making of a Rift in the Church: From Apostolic Times until the Council of Florence''. Oxford University Press, 2003.
* Chrysostom Frank. ''[http://www.unitypublishing.com/Newsletter/OrthodoxCatholic.htm Orthodox–Catholic Relations: An Orthodox Reflection]''. 1998
* Joseph P. Farrell. ''[http://dialectic.wordpress.com/ghd/ God, History, & Dialectic: The Theological Foundations of the Two Europes and Their Cultural Consequences]''. Bound edition 1997. Electronic edition 2008.
* {{Cite journal |url=https://www.academia.edu/21421032 |title=The Prerogratives of the Papal Office as the Prime Perpetuating Cause of the East–West Schism in the Modern Day  |last=Gilbert |first=Philip |date=2004 |website=Academia.edu |access-date=7 November 2019}}
* John Romanides, ''[http://romanity.org/htm/rom.02.en.the_cure_of_the_neurobiological_sickness_of_rel.03.htm The Cure of the Neurobiological Sickness of Religion, the Hellenic Civilization of the Roman Empire, Charlemagne's Lie of 794 and His Lie Today]''
* Eugene Webb. ''In Search of The Triune God: The Christian Paths of East and West''. University of Missouri Press, 2014.

{{Refend}}

==External links==
* {{Citation |last=Ware |first=Bp. Kallistos |title=Byzantium: The Great Schism |url=http://www.fatheralexander.org/booklets/english/history_timothy_ware_1.htm#n4 |publisher=Father Alexander|ref=none}}.
* [https://www.britannica.com/EBchecked/topic/587056/Schism-of-1054 Encyclopædia Britannica: ''Schism of 1054'']
* [https://web.archive.org/web/20140208192705/https://www.vatican.va/holy_father/paul_vi/speeches/1965/documents/hf_p-vi_spe_19651207_common-declaration_en.html Joint Catholic-Orthodox Declaration of Pope Paul VI and Ecumenical Patriarch Athenagoras I, 7 December 1965]
* [http://www.bbc.co.uk/radio4/history/inourtime/inourtime_20031016.shtml BBC Radio 4 round table: ''In Our Time: Schism'' (16 October 2003)] (audio)
* {{Citation |title=East–West Schism |url=http://www.orthodox.org.ph/content/view/211/50/ |archive-url=https://archive.today/20120905202235/http://www.orthodox.org.ph/content/view/211/50/ |publisher=Orthodox Church in the Philippines |archive-date=5 September 2012 |url-status=dead}}.
* {{Citation |title=The Great Schism |url=http://www.orthodoxinfo.com/general/greatschism.aspx |publisher=Orthodox SCOBA}}.

{{Eastern Orthodox Church footer}}
{{History of the Catholic Church}}
{{Catholicism}}
{{Eastern Christianity footer}}
{{Christianity footer}}
{{Christian History|collapsed}}
{{Middle Ages}}
{{Byzantine Empire topics}}
{{Subject bar|portal1=Christianity|portal2=Catholicism|portal3=Christianity|commons=yes|commons-search=Category:East–West Schism|s=yes|s-search=Catholic Encyclopedia (1913)/The Eastern Schism|d=yes|d-search=Q51648}}
{{Authority control}}

{{DEFAULTSORT:East-West Schism}}

[[Category:East–West Schism| ]]
[[Category:1050s in the Byzantine Empire]]
[[Category:1054]]
[[Category:11th-century Catholicism]]
[[Category:11th-century Christianity]]
[[Category:11th-century Eastern Orthodoxy]]
[[Category:Christendom]]
[[Category:Christian terminology]]
[[Category:Christianity in the Byzantine Empire]]
[[Category:Filioque]]
[[Category:Schisms in Christianity]]
[[Category:Byzantine Empire–Holy See relations]]
[[Category:1050s in religion]]
[[Category:Rusyn history|1054]]
[[Category:Western culture]]