Why did the Schism of 1054 deepen the divide between Rome and Constantinople?

The Schism of 1054 was the culmination of a long-standing process of estrangement between the Roman and Byzantine churches, driven by deep-seated cultural, political, and theological differences.123

The divide was deepened by several key factors:

• Authority and Primacy: The Roman papacy increasingly asserted its claim to universal authority, a concept never acknowledged in the East. Eastern churches maintained that the importance of local sees—such as Rome, Alexandria, Antioch, and Constantinople—should be determined by political and numerical significance, with doctrinal disputes settled by ecumenical councils.12
• The Filioque Controversy: A major theological rift centered on the Nicene Creed. The Western church unilaterally added the Filioque clause ("and the Son"), which Eastern theologians rejected as a violation of the creed and a misunderstanding of the Holy Trinity.14
• Disciplinary and Ritual Differences: Tensions were exacerbated by Western enforcement of clerical celibacy, the use of unleavened bread in the Eucharist, and limitations on the right of confirmation.15
• Political Rivalry: Competition between the Byzantine Empire and the rising powers of the West, alongside the influence of Frankish clergy in Rome, created an environment where reconciliation became increasingly difficult.52

These tensions resulted in mutual excommunications in 1054, formalizing a rift that was later solidified by events such as the Latin capture of Constantinople in 1204.13