By Bart D. Ehrman, The University of North Carolina, Chapel Hill
Christianity still had not become the official religion of the Roman state under the rule of Constantine’s sons. After the death of Julian the Apostate, every Roman emperor was Christian. Some were more outspoken and forceful in their support of the Christian church than others. One of the most forceful of all was Theodosius I, who ruled from 379 to 395 CE.

What Theodosius I Wanted
By this time, Christianity had grown by leaps and bounds. If there were two or three million Christians at the beginning of the 4th century, by the end of Theodosius’ reign, there were 25 or 30 million.
Theodosius himself was a deeply committed and religious Christian who promoted the Christian cause in a very serious way, leading eventually to the Christianization of the empire and the establishment of Christianity as the official religion of the state. His form of faith was what is normally termed orthodox.
Among other things, that means he opposed the Arian understanding of Christ and advocated the strong doctrine—the Trinity was Father, Son, and Holy Spirit. Those three were of the same substance and were completely equal for all time. Theodosius worked to make this the faith of all people.

Theodosius I Restricted Paganism
This may not seem a particularly important aspect of leadership in our day, but it was quite a serious matter in the context of Rome in the 4th century, when emperors sometimes used civil power to enforce religious orthodoxy. For example, by sending powerful bishops into exile away from their cities where they had exercised enormous social and political influence.
Theodosius had been one of the top military commanders of the Roman armies before being appointed emperor in 379 CE. As happened throughout this period, much of his reign involved military operations in trying to keep the empire safe from foreign invasions.
But what matters for our purposes are his efforts to advance the Christian cause. Most important to that end was the legislation passed under Theodosius reign that was designed to limit, restrict, and in a sense, illegalize pagan cultic practices in order to promote the Christian faith.
Roman Imperial Legislation
It will be important to remember that Roman imperial legislation was quite different from what we know of as federal law in the modern world. Decrees coming from the imperial authorities in Rome itself expressed the imperial will, but almost never could they be enforced and often they were ignored.
Local rulers normally took the legislation as advice and directives rather than as strict instructions that had to be adhered to at all costs. Even so, enforcement could and did happen in many places. Since the laws did express the political direction of the empire and the will of the ultimate ruler, both administrative officials and private citizens, or even mobs could take matters into their own hands and act accordingly.
This article comes directly from content in the video series The Triumph of Christianity. Watch it now, on Wondrium.
Disastrous Laws for Pagans
In the end, once imperial legislation came to be directed against traditional pagan cults, it spelled disaster for them. A number of the laws ascribed to Theodosius proscribe pagan cultic practices and enforce Christian orthodoxy. Unlike so much previous legislation designed for just one locality or another, many of these were meant to have wide ranging application.
Early in his reign, Theodosius provided a major disincentive for anyone inclined to revert to paganism. An apostate from Christianity would not be allowed to make a will. That is to say, anyone who deconverted could not pass on any worldly property to heirs.
Moreover, any apostate who already had a will was to have it nullified. Since wealth tended to stay within families and since this was a major concern for most aristocrats, these laws provided major disincentives to leave the faith.
Increasing Pressure on Pagan Cults
Theodosius issued legislation that proscribed sacrifices, divination, and the use of temples to these ends. In 391 CE, in the most comprehensive law to date, he directed, “No person shall pollute himself with sacrificial animals; no person shall slaughter an innocent victim; no person shall approach the shrines, shall wander through the temples or revere the images formed by mortal labor, lest he become guilty by divine and human laws.”
The law further stipulated that any judge who participated in worship in pagan temple would be fined 15 pounds of gold. Governors of consular rank and their staff members who did so would be fined six pounds of gold.
Nearly two years later came a law prohibiting pagan cult of any kind even in the privacy of one’s own home, including worshiping the various household gods, gods known as the Lares, who are guardian spirits of the home or the Geniuses, the divine part or double of the human head of the household, the paterfamilias. Or the Penates, gods of the pantry who helped protect the home.
The penalties were stiff—confiscation of property and large fines—as were the penalties for judges who connived in cases of violation. They would be fined 30 pounds of gold.
Common Questions about How Theodosius I Supported Christianity in the Face of Paganism
Theodosius I believe in a kind of orthodox Christianity. He was against the Arian understanding of Christianity and believed in and promoted the doctrine of the Trinity. The Trinity meant the Father, Son, and Holy Spirit, which were made of the same substance and equal to each other forever.
Legislation given out by the Roman Empire wasn’t regarded as laws that everybody had to abide by, like what we might think when we think of federal laws. Instead, they were viewed as guidance for rulers of smaller counties who had their own laws. But they were harbingers of change in the long run, such as Theodosius I’s laws against paganism.
One of the laws that Theodosius I passed was that those who converted back to paganism from Christianity could no longer write a will. Since, in those days, wealth tended to stay in families, this made converting to paganism a difficult choice.