Making a Byzantine emperor began, in the empire's earlier centuries, as an unambiguously military and civil act rather than a religious one: the new ruler was acclaimed by the assembled army, senate and people, and in the oldest form of the ritual was physically raised aloft on a shield, a Roman military custom the Byzantines inherited and continued long after the empire had become thoroughly Christian in every other respect. Religious coronation entered gradually rather than displacing the older acclamation outright, and by the middle Byzantine period the two had fused into a single ceremony, with the shield raising, where it survived, understood as an archaic preliminary to the properly sacred act that followed.
From roughly the seventh century the patriarch of Constantinople's placing of the crown became the ceremony's defining religious moment, normally performed in the Hagia Sophia, the empire's great cathedral, and the developing rite drew Byzantine political theology, which held the emperor to be God's appointed representative on earth, isapostolos in some formulations, equal to the apostles, into direct ceremonial expression in a way that shaped Christian ideas of sacred kingship across the medieval world far beyond Byzantium's own borders.