The Great Schism of 1054 AD was the formal split between the Roman Catholic Church in the West and the Eastern Orthodox Church in the East. It marked the culmination of centuries of theological, political, and cultural differences between the two branches of Christianity. The division remains to this day and represents one of the most significant events in Christian history.

Key Causes of the Schism:

1. Theological Disputes:
   • Filioque Clause:
     • The Western Church added the phrase “and the Son” (Filioque) to the Nicene Creed, stating that the Holy Spirit proceeds from both the Father and the Son.
     • The Eastern Church rejected this, arguing it was an unauthorized alteration of a fundamental creed.
2. Ecclesiastical Authority:
   • The Papal Primacy:
     • The Roman Church claimed the Pope, as the Bishop of Rome, held universal authority over all Christians.
     • The Eastern Church upheld a conciliar model, where all bishops, particularly the patriarchs of major cities (Constantinople, Alexandria, Antioch, and Jerusalem), shared authority equally.
   • Role of Constantinople:
     • The Eastern Church, centered in Constantinople, resisted the growing dominance of the Roman Pope.
3. Cultural and Linguistic Differences:
   • Language:
     • The Western Church used Latin, while the Eastern Church used Greek.
   • Philosophical Approaches:
     • Western theology leaned on legal and systematic frameworks, whereas Eastern theology emphasized mysticism and spiritual experience.
4. Political Tensions:
   • The division of the Roman Empire into Eastern (Byzantine) and Western halves in AD 395 created separate political and cultural identities.
   • Rivalry between the Byzantine Empire and the emerging power of Western European kingdoms fueled mistrust.
5. Liturgical Practices:
   • Differences in worship practices, such as the use of unleavened bread in the Eucharist in the West versus leavened bread in the East.

The Events of 1054:

1. Mutual Excommunications:
   • In 1054, Pope Leo IX sent legates to Constantinople to negotiate unity with Patriarch Michael Cerularius.
   • Disputes over authority and theology escalated, leading Cardinal Humbert, one of the legates, to place a bull of excommunication on the altar of the Hagia Sophia.
   • In response, Patriarch Cerularius excommunicated the legates, formalizing the split.
2. Symbolic but Not Immediate:
   • While 1054 is marked as the year of the schism, the division deepened over centuries rather than occurring suddenly.

Consequences of the Schism:

1. Establishment of Two Churches:
   • Roman Catholic Church (West): Led by the Pope in Rome.
   • Eastern Orthodox Church (East): Led by a group of patriarchs, with the Patriarch of Constantinople as the “first among equals.”
2. Mutual Hostility:
   • Relations between the two branches worsened during events like the Crusades, particularly the Fourth Crusade (1204), when Western Crusaders sacked Constantinople.
3. Theological and Cultural Divergence:
   • The two churches evolved distinct theological emphases, liturgical traditions, and governance structures.

Modern Efforts at Reconciliation:

1. Second Vatican Council (1962–1965):
   • The Catholic Church acknowledged the importance of Eastern traditions and sought dialogue.
2. Mutual Lifting of Excommunications (1965):
   • Pope Paul VI and Patriarch Athenagoras I formally lifted the mutual excommunications from 1054.
3. Ongoing Dialogue:
   • Catholic and Orthodox leaders continue to work toward healing the divide, focusing on shared beliefs and mutual respect.

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