Roman Empire

Roman religion was public business before it was private belief. The colleges of pontiffs and augurs were magistracies, the calendar of festivals was a state calendar, and the emperor held the office of pontifex maximus; what mattered was that the rites were performed correctly on behalf of the people, not that anyone felt anything while performing them. On the same principle the empire was hospitable to almost every god it met. Egyptian Isis, Persian Mithras, Anatolian Cybele and Syrian Jupiter Dolichenus all acquired Roman temples and Roman worshippers, and Roger Beck's work on the Mithraic cult shows how thoroughly such a religion could be reimagined inside a Roman idiom.

What the empire required was not exclusive loyalty but participation. Sacrifice to the emperor's genius and to the gods of the state was a civic act, and only two communities refused it. Jews were granted a standing exemption, understood as an ancestral custom of great antiquity; Christians, who could claim no such antiquity and who recruited across the whole population, were not.

Persecution was therefore intermittent and, when it came, administrative. Decius in 250 required every inhabitant to sacrifice and issue a certificate; Valerian struck at clergy and property in 257; and the Great Persecution launched by Diocletian in 303 burned scriptures and demolished churches. None of them lasted, and each produced martyrs whose cults outlived the emperors who made them.

Within a decade of the Great Persecution the position reversed. Constantine took the west in 312 and issued with Licinius the settlement of 313 that granted free exercise to Christians and restored their confiscated property, and he then began funding basilicas, exempting clergy from public burdens and, in 325, summoning the bishops to Nicaea to settle a doctrinal quarrel he did not understand but could not allow to divide his empire. H. A. Drake has argued that Constantine's aim was a broad consensus rather than the suppression of paganism, and that the intolerance which followed was driven by bishops more than by the throne.

The direction was not settled at once. Julian, emperor from 361 to 363, attempted a restoration of the old cults with a reorganised pagan priesthood modelled on the church he had abandoned, and died before it could take hold. In 380 Theodosius I and his colleagues issued the edict at Thessalonica requiring all peoples to hold the faith of Nicaea, and in 391 and 392 he prohibited sacrifice and closed the temples.

Ramsay MacMullen's study of how the empire actually became Christian warns against reading these laws as a description of what happened: conversion was slow, uneven and driven far more by miracle, patronage and pressure from below than by imperial decree. When the western emperors ended in 476 the church was the one imperial institution still standing, holding the shape of the provinces it had grown inside.