The Edict of Thessalonica

The law issued in 380 in the names of Theodosius, Gratian and Valentinian II is short. It commands that all the peoples under their rule shall practise the religion which the apostle Peter delivered to the Romans, as followed by the bishop Damasus of Rome and by Peter, bishop of Alexandria, namely belief in the single deity of Father, Son and Holy Spirit in equal majesty and holy Trinity. Those who follow it shall take the name of catholic Christians; the rest are judged demented and insane, shall bear the infamy of heretical teaching, and are to be punished by divine and by imperial vengeance.

Two features of the drafting are worth attention. The law does not state the doctrine at length; it identifies it by naming two living bishops whose communion is the test. And it takes the name catholic, which the church had used of itself for two centuries, and makes it a legal category with consequences attached.

The immediate context was the Arian dispute, which had run for two generations with imperial support shifting between parties. Theodosius ended the shifting by legislating. The council he called at Constantinople the following year confirmed the doctrinal settlement, and within a decade further laws prohibited sacrifice and closed temples of the older cults.

The consequences of this law fall into two classes, and both belong in the record.

For the church, establishment brought resources, legal standing and reach that no voluntary body could have achieved, and it is the reason a large proportion of the material in this atlas exists at all: the manuscripts, the buildings, the councils, the endowed schools. It also brought the state into doctrine permanently. Emperors called councils, exiled bishops, and treated theological dissent as sedition, because after 380 it legally was.

For everyone else, the law made religious difference a punishable status. Its immediate targets were other Christians, and heretic in Roman law from this point means a category of person with reduced rights. The older cults were suppressed within a generation. Jews retained a legally protected but steadily degraded position, and the accumulating disabilities in the same book of the Theodosian Code are the beginning of a legal tradition that ran for a thousand years.

The atlas records the law rather than judging it, but the sequence it belongs to is worth stating plainly: a community persecuted within living memory acquired the machinery of persecution and used it. That is not a peculiarity of Christianity, and later entries in this atlas show other traditions in the same position making the same choice.