In the West, the role of religion in power has evolved over time. From the fall of the Roman Empire and the Byzantine Empire's embrace of Christianity under Emperor Constantine to the rise of the Holy Roman Empire in the Middle Ages and the Reformation movement led by Martin Luther, these transitions were fraught with protracted periods of warfare where religion and dynastic-political interests were inextricably linked.
Constantine’s conversion to Christianity in the third century AD came at a time when the Roman Empire was experiencing economic and social upheaval, civil wars, power struggles, invasions by Germanic tribes, and the rise of Diocletian. Therefore, the empire felt compelled to shift its capital eastward to Constantinople, designating it the seat of the Eastern Empire.
Emperor Constantine understood the link between polytheism and polyarchy and found that the monotheism of Christianity provided a framework to concentrate power in a single political figure, the Roman Emperor, who could rule unchallenged—not as a man elected by his peers but as a divine leader chosen by heaven. Pagan thinkers of the time argued that the unification of the gods reinforced despotism.
When the Holy Roman Empire arose in the West following the coronation of Charlemagne by the Pope, the Byzantines saw it as an attempt to shatter their exclusive hold on divine kingship, further widening the divide with the Roman Church—a rift that would culminate in the complete schism between the Eastern and Western churches.
