The Chalcedonian Divide: How a Fifth-Century Council Split Christianity and Shaped the Modern World The Council of Chalcedon in 451 CE was meant to unite Christianity by defining Christ's nature, but instead it triggered one of history's longest religious schisms. This comprehensive narrative explores how theological debates over whether Christ had "one nature" or "two natures" became entangled with imperial politics, cultural identity, and ecclesiastical power struggles, dividing the ancient churches of Egypt, Syria, Armenia, and Ethiopia from Constantinople and Rome for fifteen centuries. Drawing on extensive historical sources and modern scholarship, this book traces the controversy from its roots in the rivalry between Alexandria and Antioch, through the dramatic confrontations at the Council of Ephesus, to the violent aftermath of Chalcedon that saw patriarchs murdered and churches burned. It examines how Byzantine persecution paradoxically gave way to greater religious freedom under Islamic rule, how figures like Jacob Baradaeus built parallel church hierarchies while disguised in rags, and how twentieth-century ecumenical dialogues finally revealed that the schism was based largely on linguistic misunderstanding rather than genuine theological disagreement. This is the story of how words divided the Christian world-and how patient dialogue is finally healing wounds that lasted a millennium and a half.