Rome and Constantinople: The road to the Great Schism

Between AD 787 and 1054, the Latin West and Greek East did not pass from unity to schism in a single dramatic moment. They remained linked by a common Chalcedonian and Nicene inheritance, sacramental life, episcopal structures, saints, missions, and repeated efforts at communion, even as political, linguistic, canonical, liturgical, and jurisdictional differences accumulated. This chapter reconstructs that gradual estrangement from the unsettled aftermath of the Second Council of Nicaea through the Carolingian-Byzantine rivalry, the Photian controversy, missionary competition in the Balkans and Slavic lands, the spread of the Filioque in the Latin Creed, the reforming papacy of Leo IX, and the events of 1054. It gives particular attention to the development of Roman primacy from ancient honor and appellate influence toward stronger claims of universal jurisdiction; Constantinople's countervailing appeal to conciliar order, canonical precedence, and imperial status; the theological and procedural dimensions of the Filioque; differences over clerical marriage, fasting, and Eucharistic bread; and the strategic importance of Bulgaria, Moravia, Rus, and southern Italy. The chapter argues that 1054 is best treated as a conventional milestone within a longer process: Humbert's bull and the Constantinopolitan response targeted persons, did not instantly sever every relationship between the churches, and gained their later symbolic weight because subsequent conflicts hardened the division. A Sola Scriptura assessment affirms the biblical call to doctrinal truth and visible unity while testing papal universal jurisdiction, unilateral alteration of an ecumenical creed, pneumatological formulas, and identity-making liturgical customs by the apostolic Scriptures rather than by antiquity or institutional prestige alone.

Keywords: Great Schism; Rome; Constantinople; papal primacy; Filioque; Photius; Charlemagne; East-West relations