The Conversion of Constantine

The Conversion of Constantine May 28, 2018

Editor’s Note:  In celebration of his latest book, The Triumph of Christianity: How a Forbidden Religion Swept the World, Clergy Project member and celebrated author, Bart Ehrman, shares the beginning of the first chapter. It’s background on The Emperor Constantine’s role in the ultimate success of Christianity.  I found it to be fascinating. I bet you will, too. //Linda LaScola, Editor


By Bart Ehrman

Few events in the history of civilization have proved more transformative than the conversion of the emperor Constantine to Christianity in the year 312 CE.  Later historians would sometimes question whether the conversion was genuine.  But to Constantine himself and to spiritual advisors close to him, there appears to have been no doubt.  He had shifted from one set of religious beliefs and practices to another.  At one point in his life he was a polytheist who worshiped a variety of pagan gods — gods of his hometown Naissus in the Balkans, gods of his family, gods connected with the armies he served, and the gods of Rome itself.  At another point he was a monotheist, worshiping the Christian God alone.  His change may not have been sudden and immediate.  It may have involved a longer set of transitions than he later remembered, or at least said.  There may have been numerous conversations, debates with others, and reflections within himself.  But he dated the event to October 28, 312.  At that point he began to consider himself a Christian.

The results were tremendous, but not for the reasons often claimed.  It is not that Constantine eventually made Christianity the state religion.  Christianity would not become the official religion of Rome until nearly eight decades later under the reign of emperor Theodosius I.  And it is not that Constantine’s conversion was the single decisive turning point in the spread and success of the Christian religion, the one moment that changed all history and made the Christian conquest a success.  At the rate it was growing at the time, Christianity may well have succeeded otherwise.  If Constantine had not converted, possibly a later emperor would have done so, say, one of his sons.   Instead, what made Constantine’s conversion revolutionary was that the imperial apparatus that before then had been officially opposed to Christianity and worked hard, in some regions of the empire, to extirpate it completely, suddenly came to support it, promoting Christianity instead of persecuting it.  Constantine did not make Christianity the one official and viable religion.  He made it a licit religion, and one that enjoyed particular, even unique, imperial privileges and funding.  This support did indeed advance the Christian cause.  The recognition that this faith was now favored from on high appears to have contributed to the already impressive numbers adding to the Christian growth, including the conversion of increasing numbers of imperial and local elites, whose resources had until then funded (and thus made possible) the religious practices of their pagan world.

As important as Constantine’s conversion was to the welfare of the Christian movement, it is surprisingly difficult to describe what he converted from.  Modern historians of religion who speak of conversion can mean a variety of things by it.  Possibly it is simplest to keep the meaning broad and use the term to refer to a decided shift away from one set of religious practices and beliefs to another.   That certainly happened with Constantine.  At a moment that seemed, at least later in hindsight, to be clear and well-defined, he stopped being a pagan and became a Christian.

Conversion was not a widely known phenomenon in antiquity.  Pagan religions had almost nothing like it.  They were polytheistic, and anyone who decided, as a pagan, to worship a new or different god was never required to relinquish any former gods or their previous patterns of worship.  Pagan religions were additive, not restrictive.

Christians, on the other hand, did require a choice.  Converts were expected to forego the worship of all the other gods and revere the Christian God alone.   Only Judaism had similar expectations and demands.  Among pagans – that is among the 93% or so of the world that by custom, habit, and inclination worshiped multiple gods – worshiping a range of divine beings was not a religion that anyone chose.  It was simply what people did.  Being a pagan meant participating in the various religious activities associated with the official state gods, local municipal gods, personal family gods, and any other gods that were known to be involved with human experience.  For everyone except Jews, and then Christians, this was more a way of life than a conscious decision.  It  was a matter of doing what everyone had always done, very much like participating in the life of the local community, with the exception that most people were involved with only one community but could be engaged in the worship of a virtually incalculable number of gods.

For that reason, paganism should not be thought of as a solitary “thing” but as hundreds – thousands – of things.  Those who practiced traditional religions – in other words, just about everyone – would never have recognized themselves as participating in something called “paganism” or, indeed, any kind of “ism.”   There was not a thing there, nothing that could be named so as to sum up the totality of all the non-Jewish religious observances or beliefs or cultic practices of prayer and sacrifice ubiquitous in the culture.  No pagan would have understood what it would mean to call themselves pagan.  They were simply acting in time-honored ways of worshiping the gods.

Constantine, like everyone else who was not raised Jewish or Christian, participated in this worship.  But he gave it up to follow the one God of the Christians.  The narrative of how Constantine became a Christian is both intriguing and complex.  It involves issues that we today would consider strictly social and political and other issues that we would consider strictly religious.  But in the early fourth century – as in all the centuries of human history before that time – these two realms, the socio-political and the religious, were not seen as distinct.  They were tightly and inextricably interwoven.  On just the linguistic level, there were no Greek or Latin terms that neatly differentiated between what we today mean by “politics” and “religion.”   On the practical level, the gods were understood to be closely connected with every aspect of the social and political life of a community, from the election of officials, to the setting of the annual calendar, to the laws and practices that governed social relations, such as marriage and divorce, to the administration of civil justice, to the decisions and actions of war, to all the other major decisions of state.    The gods were active in every part of social and political life, and the decisions made and actions taken were done in relation to them.

On the imperial level this meant that it was widely known (and genuinely believed, by most) that it was the gods who had made the empire great.  The empire responded by sponsoring and encouraging the worship of the gods.  Doing so would promote the commonweal.  There was no sense that there was, should be, or could be a separation of church and state.

Starting in the mid-third century, the emperors themselves sensed this full well and acted accordingly.  That is why, some years before Constantine converted, the Christian religion had been persecuted by order of the state.  The Christians refused to worship or even acknowledge the gods of empire, claiming in fact that these were evil demonic beings, not beneficent deities that promoted the just cause of the greatest empire the world had ever known.  The refusal to worship was seen by others to be dangerous to the well-being of empire and thus to the security of state.  And so the decision to persecute – which seems to us, perhaps, to be a strictly religious affair – was at the time inherently socio-political as well.  The Christians were to be removed like a cancer from the body of state.  No emperor came to believe this more firmly – in no small part because of the alarming growth of this cancer – than Constantine’s predecessor on the throne, Diocletian, who instigated the most vicious empire-wide persecution ever seen.  Constantine himself was later to rescind the demands of this persecution.  But while it was still in process, he converted.

This conversion proved to be a lynchpin of imperial history, not just for the fate of the Christian religion but also for the workings of the Roman state.  We will look at the persecution of Diocletian in a later chapter, and at the broader biography of Constantine in another.  For now we are interested specifically in his conversion and how it radically changed the balance of power, both for the persecuted Christians and for the running of the Roman government.  To make sense of the conversion we need to understand some of the political and religious backdrop to the story.


Bart Ehrman, Religious Studies at the University of North Carolina at Chapel Hill.

Bio: Bart D. Ehrmanis the James A. Gray Distinguished Professor at the University of North Carolina at Chapel Hill. He came to UNC in 1988, after four years of teaching at Rutgers University. At UNC he has served as both the Director of Graduate Studies and the Chair of the Department of Religious Studies.

A graduate of Wheaton College (Illinois), Bart received both his Masters of Divinity and Ph.D. from Princeton Theological Seminary, where his 1985 doctoral dissertation was awarded magna cum laude. Since then he has published extensively in the fields of New Testament and Early Christianity, having written or edited twenty-six books, numerous scholarly articles, and dozens of book reviews. For more detail, read here.  Bart is also an original member of The Clergy Project.  He has given The Rational Doubt Blog permission to repost public blogs, including this one, fromThe Bart Ehrman Blog.

>>>>>Photo Credits:

By I, Jean-Christophe BENOIST, CC BY 2.5,  ;  By Dan Sears – UNC-Chapel Hill, CC BY 4.0,

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  • Kevin K

    It is interesting. It seems to indicate that the entire concept of a “religion” as opposed to a set of cultural expectations/handed-down superstitious beliefs, is a somewhat later invention. Surely, the Romans (et al) did not call themselves “pagan”.

    • carolyntclark

      from Ancient Origins.”…In the Latin west, it was more common for the various religions to refer to themselves by their ethnic origins rather than by the gods they worshipped—they simply referred to themselves (in their own language) as Romans, Greeks, Egyptians, etc., simultaneously insinuating their religious factions as well. This form of labeling was largely due to the fact that the political and religious aspects of life were a unified entity.”

      • Kevin K

        Since the Roman Senate had the power to declare (vote) someone as a god, this makes sense. I wonder when the separation of church and state began?

        • ElizabetB.

          A good question for us who haven’t been really thinking about it! Poking around, my guess would be the Enlightenment — the “long 18th century” (1685-1815). Interesting pdf from the European Liberal Forum if we google “Separation of Church and State in Europe”

    • Foxglove

      The Latin word “paganus” originally meant a “countryman, peasant, villager, rustic.” I believe the reason the term was applied to “non-Christians” was that country people tended to cling to the old polytheism longer than urban people did.

      • Kevin K

        If my observations are correct, we’re in much the same boat today wrt religion. I see it having a much stronger hold in rural areas than in the city.

        But I may be looking at a marker for poverty — I didn’t hang around the poor areas of the city much, and most especially not their churches. Confirmation bias and all that.

        • Foxglove

          That’s certainly the case with Ireland–rural areas are noticeably more conservative than urban areas in religious matters. We saw this in the last two referenda. Rural areas tended to be 15-20% more conservative than urban areas. That said, the rural areas did by and large support progressive causes–just not as heavily as the urban areas did.

          • Kevin K

            It’s that darned interwebs. Tubes … they’re tubes!!!

  • carolyntclark

    This has spurred me to more on-line reading… Ancient Origins….”as far as ancient sources can tell, it wasn’t until the Late Roman Empire that the term “pagan” began to be used instead, as it was an easy way to lump all the non-Christians together in conversation, decrees, etc. It rose to popularity as a matter of convenience rather than of accuracy and respect. ”
    Can someone tell me what term was used by the post-Commandments Israelites for the polytheists of the day ?

  • ThaneOfDrones

    I am currently reading The Closing of the Western Mind by Charles Freeman, which has a lot of material about this time period, although I understand it was not well received by critics.

    Freeman points out that Constantine’s version of the Christian God is a god of victory in battle, which was a new direction for Christianity.

    Also, the 4th century was an important time in the development of Christian doctrine; with the development of the concept of the Trinity, and the life-long virginity of Mary, the mother of Jesus. These items have very weak scriptural support but were mandated by various councils.

    • ElizabetB.

      Interesting title! Thanks for the tip! I see the NYTimes review did think Freeman did a good job with the turning points in the evolution of Christianity… and some of it sounds like a good read, as the Times remarks parenthetically, “(St. Jerome’s theory that the main purpose of marriage was to produce virgins sounds too funny to be true, but apparently is.)”
      : )

      • ThaneOfDrones

        The part which was poorly accepted was the thesis that Christianity was responsible for the “closing of the Western mind” because it caused a turning away from Greek philosophy and the scientific method. I don’t think anyone had a problem with his exposition of factual material.

        • ElizabetB.

          Thanks very much, Thane! History can sure sound complex — I’ve been reading Geering saying how it was the turn to Greek thought that encouraged early Christians to deify the human Jesus and develop the idea of trinity, foreign to the Jewish origins (including the Jesus figure himself).

          I think he would agree with Freeman’s critics, as he says, “It is too little appreciated that this [empirical science] arose out of the Christian culture of Western Europe; it was initiated by Christian thinkers and, initially, for Christian purposes. Roger Bacon (1214–1292), who has been named the morning star of modern science, wrote that ‘the surest method of extirpating all heresies, and of destroying the Kingdom of the anti-Christ, and of establishing true religion in the hearts of men, is by perfecting a true system of natural philosophy’.” [Christianity without God, 13-4]

          He recognizes how there are always reactionary forces against any change, so it’s been a struggle. Thanks again for the thesis explored!

  • See Noevo

    Some similarity to Saul of Tarsus.
    One minute he’s killing Christians all over the place, the next, as the apostle Paul, he’s preaching for Christ all over the known world.

    • mason lane

      He knew a good sucker racket when he saw it, even created his own testimony scenario to garner a shepherd’s authority among the hapless sheep. But his franchise story contradicted the franchise stories of whoever were Matthew, Mark, Luke, John which all had their internal contradictions and contradictions of each other. Oh, well, sheep never were too adept at reading comprehension or critical thought.

      Contradictions in the Bible are like the HIV virus in AIDS. Here’s 532 contradictions, certainly not all, but it helps one get the idea how contradictions, historical lies, deity immorality, and fairy tales, with a dash of aphorisms & proverbs, are essential to the Bible stew.

      • Jim Jones

        > But his franchise story contradicted the franchise stories of whoever were Matthew, Mark, Luke, John.

        Of course he wrote his 4 (or 6) books 100 years before the gospels.

  • ElizabetB.

    I’m reading Lloyd Geering’s “Christianity without God” (after reading Maguire’s), and Geering sees a natural progression from “Christendom,” when people assumed their thought-world was the only one — to the idea of “Christianity,” recognizing that there are other ways of perceiving reality like “Judaism,” “Buddhism,” etc — to today’s secularism, evolving into a new global secular society.

    ” [T]he modern atheist who rejects the notion of God in the interests of truth may be manifesting more faith than the traditional theist. The assertion that one needs to believe a particular creed or set of doctrines in order to have faith is an invitation not to faith but to credulity.” [p.26]

    “As people have increasingly questioned and abandoned specific Christian beliefs and practices of the past they have been slowly disengaging themselves from the organization of the church. They have become the ‘unchurched’ or what Bishop Spong has called ‘the church’s alumni association’. Although they have not established a new organization to replace the church they have, often unknowingly, been building a new kind of society — a global secular society…. This emerging secular world is not Christian in the way the medieval ‘Christian world’ was. But neither is it anti-Christian. It is rightly called ‘post-Christian’, a term which indicates both its indebtedness to its Christian roots and its new character. It is post-Christian in much the same way as the newly emerging Christian stream of the ancient world was post-Jewish.” [pp.32-3]

    If one followed this line of thought, I wonder what the term for this “global secular society” might come to be

    • mason lane

      Yep, been a happy member of the “Church’s Alumni Assc.” for 47 years now. “Global Secular Society” sounds perfect. A society built upon the truths of science, ethics, rational thought & reason not ancient fairy tales & myths created by very imaginative but sadistic goat & sheep herders.

      • ElizabetB.

        His disussions of “faith” (presumably within this global secular society) have been reminding me of your posts about the things you have faith in, or believe in…. He quotes Cantwell Smith — “Faith is a quality of human living. At its best it has taken the form of serenity and courage and service; a quiet confidence and joy that enable one to feel at home in the universe, and to find meaning in the world and in one’s life, a meaning that is profound and ultimate, and is stable no matter what may happen to oneself at the level of immediate event” and Hartshorne’s “The Faith to Doubt” saying “People today are not in need of assurances about the truth of doubtful beliefs. They need the courage to doubt. They need the faith by which to reject their idols.” [Geering p.26]

  • Mark Rutledge

    Thanks Bart. Good little history lesson for the day!

  • carolyntclark

    I’m inspired to do more reading on Hypatia. Off to the library.

    • ElizabetB.

      Neat! That’s a familiar name, but looking at wiki I realize there’s much I haven’t been aware of! Inspiring! thanks!

  • Jim Jones

    Bart Ehrman: “Few events in the history of civilization have proved more transformative than the conversion of the emperor Constantine to Christianity in the year 312 CE.”

    I’ll take “Things that never happened” for $1000, Alex.

    Where is the evidence? Not on his arch. Not on his column. Nowhere AFAIK. His mother & wife? Sure. Constantine? No.