The Christian Roman Empire

For nearly three centuries Christians lived under an empire that could, at any moment, turn on them. Waves of persecution came and went, and the martyrs' graves became the Church's first altars. Then, in 312, the emperor Constantine won the battle of the Milvian Bridge under the sign of the Cross, and the world tilted. The following year, by the agreement remembered as the Edict of Milan (313), Constantine and his co-emperor Licinius granted Christians — and everyone else — the freedom to worship openly. The blood-soaked centuries of the persecutions were over.

It is worth being precise about what Constantine did and did not do. He did not make Christianity the empire's official religion; that came later. He legalized it, lavished patronage on it, built great churches, and — decisively for the Church's future — summoned the bishops to the First Ecumenical Council at Nicaea in 325 to settle the Arian crisis. His own baptism waited until he lay dying in 337. What he opened was a door: for the first time, the Church could act in the daylight, and an emperor had made its business his own.

The empire became officially Christian under Theodosius I. On 27 February 380, together with the western emperors Gratian and Valentinian II, he issued the edict remembered by its opening words, Cunctos populos — the Edict of Thessalonica — declaring that the empire's peoples should hold the Nicene faith in the Holy Trinity professed at Rome and Alexandria. The next year Theodosius convened the Second Ecumenical Council at Constantinople (381), which completed the Nicene Creed. Over the following years the old public sacrifices were forbidden and the temples closed. A faith that had begun in an upper room was now the confession of an empire.

The gains were real: peace to worship, resources to build and teach, and the imperial machinery to gather bishops from across the world into councils. Nearly all seven Ecumenical Councils were called by emperors. But the Church did not mistake this for the Kingdom of God. A Christian empire could also pressure the Church, exile its bishops, and back heresies when it suited — as it did through the long Arian and iconoclast crises.

Out of this new arrangement grew the Orthodox ideal of symphonia: Church and empire as two distinct gifts of God, priesthood and kingship, meant to work in harmony for the salvation of the people rather than for one to rule the other. It was an ideal often honored in the breach. And precisely as the Church grew comfortable, thousands fled to the deserts of Egypt and Syria to keep the older, harder freedom of the martyrs alive — the beginning of Christian monasticism, the empire's conscience and counterweight.