The Council of Nicaea

325 CE — Anatolia, Roman Empire

Today: İznik, Turkey

Constantine summoned bishops from across the empire to settle what Christians actually believed, because a faith he had just legalized was tearing itself apart over whether Christ was of the same substance as God. The bishops voted, produced the Nicene Creed, and declared the losing position a heresy. An emperor with no theological training had convened the meeting and paid for it, because doctrinal unity was now a matter of imperial stability. It set the template for the next 1,700 years: religious authority and state power defining each other's limits by negotiation.

Worth knowing: The dispute that required an empire-wide council turned largely on a single Greek letter — whether Christ was homoousios (same substance) or homoiousios (similar substance) as the Father. The difference is one iota.

Pattern: Ideological movement — A belief system rises, spreads, institutionalizes, and then schisms — changing the rules people accept as legitimate.

Entry 85 of 240 in Precedent, a walk through the whole human story in order.