The Great Schism is the historical separation between the churches that became known as Roman Catholic and Eastern Orthodox. The year 1054 marks a confrontation between representatives of Rome and Constantinople. The division developed over a longer period as disputes about authority and doctrine interacted with changes in political power and relations between churches.
Three events help explain the distinction. The censures of 1054 named particular people. The conquest of Constantinople by the Fourth Crusade in 1204 deepened the rupture. In 1965, leaders in Rome and Constantinople set aside the old censures and called for further work toward communion.
What happened in Constantinople in 1054?
Pope Leo IX sent representatives led by Cardinal Humbert to Constantinople. On July 16, 1054, Humbert placed a sentence of excommunication on the altar of Hagia Sophia. Leo IX had already died, a fact that Metropolitan Job of Pisidia highlights in discussing the act’s authority. Metropolitan Job of Pisidia, address on the 1054 censures.
The joint Catholic–Orthodox declaration of 1965 identifies those named by the Roman delegation as Patriarch Michael Cerularius and two other people. It describes a corresponding sentence against the legates by the patriarch and the synod of Constantinople. The signatories distinguish those personal censures from the eventual breakdown of ecclesiastical communion. Joint Catholic–Orthodox Declaration, sections 2–4.
This distinction explains why 1054 is a marker in the history of the separation. The confrontation revealed how difficult relations had become between the two sees, or episcopal centres. Following what happened afterward shows how a dispute involving church leaders acquired a wider and lasting significance.
What did the Filioque dispute concern?
In the creed, the Latin addition Filioque is rendered “and from the Son.” It qualifies the clause about the Holy Spirit’s procession from the Father. The Greek text speaks of procession from the Father. The North American Orthodox–Catholic Theological Consultation traces the Latin wording through earlier Western use and records its inclusion when the creed was sung at a papal Mass in Rome in 1014. The change at Rome came after centuries of discussion and regional practice. The Filioque: A Church Dividing Issue?, historical discussion.
There were two related questions. One concerned how the Father, Son and Holy Spirit are related in the doctrine of the Trinity. The other concerned who could authorize a change in the wording of a creed shared by the churches. Two people could agree to study the theological meanings of the Greek and Latin expressions and still disagree about the authority to change what was recited in worship.
The 2003 consultation asked both sides to distinguish these doctrinal and institutional questions in dialogue. It also recommended that the Catholic Church use the original Greek text as the basis for liturgical and catechetical translations of this creed. The text presents these proposals to the churches as recommendations from the consultation. The Filioque: A Church Dividing Issue?, recommendations.
Authority, councils and worship
Disputes over primacy concern the role of a leading bishop and the scope of that office’s authority. Disputes over synodality concern how bishops and churches deliberate and act together. The historical question is how leadership and collective decision-making functioned at different levels, including among churches that shared a creed and recognized one another’s bishops.
Negotiations at Ferrara and Florence in 1438–39 illustrate the practical stakes. According to the joint commission’s Alexandria document, the council considered papal primacy, the Filioque and the use of unleavened bread in the Eucharist, among other issues. Its decree asserted Roman primacy and included provisions concerning the other patriarchal sees and their privileges. The agreement was signed and later rejected in Constantinople. Alexandria document, sections 1.17–1.19.
The outcome shows how different it is to negotiate a document and to secure its lasting acceptance. A proposed union affects worship, teaching and the responsibilities of bishops. Its reception therefore depends on the communities and institutions expected to live by it.
Why the Fourth Crusade mattered
In 1204, the Fourth Crusade captured Constantinople. Western crusaders established a Latin empire there, and Byzantine rule was restored in the city in 1261. The Metropolitan Museum of Art’s historical account connects this period with political fragmentation and displacement in the Byzantine world. The Catholic–Orthodox joint commission also describes plunder and the establishment of parallel Latin church hierarchies. Metropolitan Museum of Art, Byzantium. Alexandria document, sections 1.1 and 1.9.
The change of government and the establishment of competing church structures gave the division a new setting. For communities in the affected territories, questions of authority could involve who occupied an episcopal see and who directed local worship. This helps explain why later efforts to reconcile the churches had to address historical grievances and relationships as well as theological language.
Reconciliation and the work of dialogue
On December 7, 1965, Pope Paul VI and Ecumenical Patriarch Athenagoras I, together with the patriarch’s synod, expressed regret for the events surrounding the censures and removed the sentences from the life and memory of their churches. Their declaration acknowledged continuing differences and called for dialogue directed toward full communion in faith and sacramental life. Joint Catholic–Orthodox Declaration, sections 4–5.
The 2023 Alexandria document offers a later example of that dialogue. Its authors describe primacy and synodality as interdependent and consider how they can serve church unity at local, regional and universal levels. This puts a specific question on the table: how should a leading bishop’s ministry relate to the deliberation and responsibilities of other bishops and churches? Alexandria document, sections 5.1–5.6.
Conclusion
The Great Schism developed as disputes over the creed and church authority acquired lasting institutional and political consequences. The acts of 1054 are one part of that history, alongside the conquest of Constantinople, the reception of attempted unions and the later work of reconciliation. Keeping those stages distinct explains both the importance of the date and the scope of the task that Catholic and Orthodox dialogue inherited.
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