The Edict of Thessalonica

In January 379 the western emperor Gratian proclaimed the Spanish general Theodosius I his colleague and shared with him the war against the barbarians (Socrates, Church History 5.2). In Constantinople, the eastern capital, the churches had by the count of the historian Socrates been for forty years in the hands of bishops who rejected the creed of Nicaea (Socrates, Church History 5.7).

On 27 February 380 an edict was issued at Thessalonica in the names of the three reigning emperors, Gratian, Valentinian II and Theodosius, and addressed to the people of Constantinople. All the peoples under the emperors’ rule are to live in the religion that the apostle Peter delivered to the Romans and that Damasus I, bishop of Rome, and Peter, bishop of Alexandria, now follow: belief in the one deity of Father, Son and Holy Spirit, in equal majesty and a holy Trinity. Those who keep this law are to take the name of Catholic Christians. The rest are judged to be out of their minds, are to bear the infamy of heresy, and may not call their meeting places churches. They are to be punished first by divine vengeance and then by the emperors (Theodosian Code 16.1.2).

The church historian Sozomen, writing some sixty years later, ties the law to the emperor’s baptism. Theodosius, he says, fell ill at Thessalonica, was instructed and baptised by its bishop Ascholius, learned that the East and above all Constantinople were divided among many parties, and issued the law to make his own belief known, having it published in the capital so that it would spread from there (Sozomen, Church History 7.4).

The edict named a faith and threatened punishment only in general terms. Enforcement followed. Theodosius entered Constantinople on 24 November 380 (Socrates, Church History 5.6). He asked the bishop Demophilus to accept the Nicene creed, and when he refused ordered him out of the churches; two days later Demophilus began to hold his services outside the walls (Socrates, Church History 5.7). A law of 10 January 381 forbade heretics to assemble inside towns and ordered the churches everywhere restored to bishops who held the Nicene faith (Theodosian Code 16.5.6). A law of 30 July, after the First Council of Constantinople, named the bishops with whom the holders of churches had to be in communion (Theodosian Code 16.1.3).

The edict of 380 speaks of Christians only. It does not mention the old cults or the Jews (Theodosian Code 16.1.2). Laws against sacrifice came later in the reign: in 391 sacrifice and visits to the temples were forbidden, and in November 392 the ban was extended to incense, lamps and wine offered to the household gods (Theodosian Code 16.10.10–12). In it the emperors defined right belief by the teaching of named bishops and treated departure from it as an offence (Theodosian Code 16.1.2).