By Bart D. Ehrman, The University of North Carolina, Chapel Hill
One can say that after supposedly converting, Emperor Constantine certainly didn’t seem to act much like a Christian. Constantine continued to use the image of Sol Invictus, the unconquered Sun god, on his coinage after 312 CE, the date of his alleged conversion. It’s also true that in his public presentation of himself, he did not promote just the Christian cause.

Sol Invictus Could Have Been Christ
When Constantine became a dedicated follower of Christ, it was not because he converted from following Sol Invictus to following Christ; it was because he became convinced that Sol Invictus was Christ. The traditional portrayal of the sun god was a portrayal of Christ for Constantine.
Among other things, like so many other Christians throughout history and still today, Constantine never showed any interest in compelling others to convert to his religious perspective. He affirmed the truth claims of his own faith, but he showed no concern enforcing others to accept it.
And when it comes to the public statements of faith, such as those found on the Arch of Constantine, it’s important to realize that Constantine himself did not design the arch or dictate the terms of the inscription. It was conceived and constructed by others in his honor. These others were almost certainly not Christians themselves.
Constantine: Hungry for Power
Many of Constantine’s actions do not seem at all Christian, but do we evaluate whether a person is a Christian based on whether they do only the things Christians are supposed to do? On these grounds, who among us is really a Christian?
Moreover, it’s important to recall that Constantine was indeed power-hungry and that he became the sole ruler of a massive empire. He would not have lasted a day if he had tried to govern the Roman world according to the guidelines set out by Jesus in the Sermon on the Mount. But that does not mean that Constantine did not worship the Christian God and Him alone.
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A Sincere Christian
Thus, the reasons for doubting the sincerity of Constantine’s conversion are not overly persuasive, and there’s a good deal of counterevidence. We’ll never know what he was actually thinking in his head. But all external evidence suggests that Constantine really was highly committed to the Christian cause.
One of the very first things he did after the battle for Rome in 312 CE was to put an end to the great persecution and declare for the first time that Christianity was a licit religion. From there, he started providing enormous benefits to the church and its leaders.
Progressive Actions
For centuries, local aristocrats were burdened with required public service that involved considerable outlays of cash. That’s how public buildings and public services were funded. The aristocrats had to pay for them. But Constantine absolved wealthy aristocrats from these duties as long as they assumed Christian clerical positions. They were allowed to keep their wealth. Nice benefit.
He also himself bestowed fantastic funds on the church throughout the empire, providing extensive lands. And he engaged in large construction projects. With aristocrats converting, retaining their money, and imperial money going to support them, pagan cults began to starve out of existence.
Council of Nicaea
The building projects themselves are highly significant. Most famous among his churches was the church of the Holy Sepulchre in Jerusalem, built by Constantine himself. Doing so meant destroying a temple of the pagan goddess Aphrodite at the site. Most impressive was Constantine’s founding of the entire city of Constantinople, which he made an explicitly Christian city with no pagan influence in it.
Constantine was highly active in church affairs after his conversion, including both practical arguments over what kinds of Christianity were true and right and theological arguments of the most technical and even obscure nature.

Most famously, he called for and presided over the Council of Nicaea in 325 CE to help resolve the major theological controversy of his day. But more than that, we actually have writings from Constantine from his Christian period, which make it crystal clear that he supported the Christian religion.
Constantine’s Oration to the Saints
A clear example comes in a long speech that would have taken two hours to deliver, called the Oration to the Saints. The speech is an extended defense of Christianity over paganism. In it, Constantine argues that there must be one divine ruler overall. Numerous divinities would lead to cosmic chaos. There’d be no structure to the universe. With various elements and natural forces moving and shifting all over the place, with no one in charge.
Without the one God in control of all things, there’d be no order in the world. The constellations would fall out of whack. The crops would not grow, and night and day would be confused. Constantine clearly expresses his own commitment to Christ in the sermon. Explicitly declaring quote, “My proper task is to sing a hymn to Christ through my way of life and to give the thanks we owe to him for his many great benefits.”
None of this may sound completely disinterested or selfless. Constantine was definitely receiving benefits for his religious commitment. But that’s usually the point of having a religious commitment; to receive benefits from it. That was certainly the point in the ancient world. Constantine generally considered himself a Christian, even if he didn’t always behave like it.
Common Questions about the Possibility of Constantine Being an Actual Believer of Christ
Emperor Constantine‘s faith in Christ didn’t mean he no longer accepted Sol Invictus as a god; instead, he believed that they were the same figure. So there was no reason to change the image on the coins.
The important thing to remember is that Emperor Constantine had a lust for power. Also, it seems impossible that he would be able to rule a massive empire according to the Christian doctrine. And committing actions that are deemed non-Christian doesn’t mean that the person doesn’t believe in Christianity.
In this speech, Constantine defends Christianity over paganism. He argues that there has to be one divine ruler; otherwise, there would be cosmic chaos. He also expresses his faith in Christ in this speech.