Why did the Emperor Constantine choose Christianity?

Why did the Emperor Constantine choose Christianity?
I have a theory of my own (entirely unsupported I might add), and I thought I’d reality check it here in General Questions.
My theory:
Christianity, unlike polytheism, has but one god.
My take on the situation was that Constantine reckoned that a religion that had one god would be a good model for an empire that had one emperor.
This prompts a question.
Did the romans believe that Jupiter was the Emperor’s divine benefactor? What I mean by that is, was there a similar construct in ancient Rome to the well known and oft quoted “Divine Right” of kings?
All the same, it would be an imperial bitch to run an empire when some astrologer, say, Fruitloopus, started saying that while you (the Emperor) were indeed in favor with Jupiter, that Mars was angered with you.
Critique my theory, and don’t let the bastards grind you down.

I think Constantine sort of semi-converted to a form of Christianity, but did not get baptized to his death bed. It There were other monotheistic religions - Zorasterism, for one, but Christianity was the simplest and most egalitarian. I believe you had to sacrifice a bull to join the Zoraster sect, and that was kind of pricey. A cynical point of view would be that Constantine wanted more control, aligning the empire to the church would add to the emperor’s power. And the emperors of the Christian period took for granted that they could control or at least influence the church.

Romans tradition had their city descended from semi-divine founders, but a serious worship and belief in Jupiter as Rome’s benefactor was not present in the ruling class, and not much followed by the proles. There was a very strong respect for traditions among all the people for various reasons - self interest, superstition, comfort, whatever. The Romans might feel that “the gods favor” so and so, but the gods were notoriously fickle, jealous, and petty. So things could change real fast. Divine right is a concept that rulers could twist out of Christianity - you had to have one god for that, a god that would be consistent, eternal, obviously have to be a good, loving god to give you such a wonderful leader.

Virtually everybody, Christian or pagan, believed in magic and astrology - as so many people still do today. So they might not have worried about Mars being mad at you, but were afraid of spells, and saw omens everywhere.

Thanks YPOD.
This sentence of yours,
“Divine right is a concept that rulers could twist out of Christianity - you had to have one god for that, a god that would be consistent, eternal, obviously have to be a good, loving god to give you such a wonderful leader.”
is the idea that launched my very speculation.
The Roman pantheon is fickle, and changes more than a weathervane. The Christian god provides a very reliable anchor for an absolute monarch.
The thing is, it seems like such a good idea, and that’s why I’m guessing Constantine was thus motivated.

Salaam aleikum
As genial general, Constantinus put himself under the protection of the God who was the most popular, and certainly the most popular among his soldiers: Helios Apollo. He is described as the son of Helios Apollo and thus played very well with the sensitivities and religious tendencies of his time.

The question that rises there is if he yes or no used Christianity between 302 and 312. The story about his conversion during the campaign against Maxentius is despite what is told by the panegyrici at the very least very questionable.

His vision of Christ on the evening before the battle at the Pons Milvius, with the message that if he would put a certain sign on the shields of his soldiers this would give him victory (in hoc signo vinces) is legendary. As the word says it itself.
This story is explained after his victory on different ways.
The Christians of course claim he had that vision and he had put a cross sign on the soldier’s shields.
But most likely the shields were just decorated with the asterisk liking symbol of the Sun God Helios Apollo: Sol Invictus.

There is also an other claim that Constantinus was a real convinced Christian. The so-called Edict of Milan in 313 by which the freedom of religion was proclaimed “for the first time”.
Also here we must nuance because first of all we already have the tolerance edict of Galerius in 311; shortly before his death in Sofia. The Latin original is preserved by Lactantius and an adapted Greek translation by Eusebius.

The fact that once an edict was announced by one of the tetrarchs it thus should count for the whole empire was of course only a theory. Maximus Daia didn’t apply it for his part of the empire and kept persecuting in good order the Christians.

Secondly it was not Constantinus, but Licinius who designed the Edict of Milan while Constantinus only signed it as his colleague emperor.
Thirdly, this Edict of Milan was not designed for the Western part of the Emperium, which was that of Constantinus, but for the Eastern part, where Maximus Daia ruled. As we have seen, Maximus Daia didn’t care and kept persecuting the Christians, also after the tolerance edict of Galerius.

Since Licinius was beaten by Constantinus in 324, he looses everything and this is the way the Edict of Milan came to be described as one of Constantinus.

If we then come to the installation of Constantinople as capital, we see all over that Constantinus kept the old pagan rites and buildings at their place and extended and renewed them. Nevertheless he and his mother Helena did also much in favour for Christianity.

At the very least one can conclude that the relationship between Constantinus and Christianity was one of ambiguity. There was no talk about baptism before he died and then he even got baptized by an Arian. If we even have to believe that story because the all-Christian sources are most colourful coloured by Eusebius.
Salaam. A

Can you provide cites?
Thank You.


The history of the Byzantine Empire was part of my studies.
So this post is me in a “translating myself”.

I you like I can give you some bibliography to inform yourself about the Byzantine Empire, but I don’t know which languages you read.

In any case, there is since 1991 finally an all-covering encyclopedia
The Oxford Dictionary of Byzantium,
3 volumes.
New-York/Oxford, 1991
Head-editor was A.P. Kazdhan.
Although this encyclopedia received from the beginning many critique (for example: it has not enough lemmata), it is an indispensable work-instrument for everyone who wants to get an end on the road for gathering information about an issue.

Salaam. A

The short answer is that he had a vision during a battle against Maxentius at Milvian Bridge in 312 AD. He related to Bishop Eusebius of Caesarea that he had seen a cross with the words “In hoc signo vinces”. It means “In this sign you shall conquer”. There is some controversy, quite naturally, but versions of the story are easy to track down. Here is one source:


I discover here on my database some yuseful adresses and links about Byzantium if you want to find something about it via the internet.



Salaam. A

I don’t think this is true. The Egyptians certainly had more than one god, and the pharaohs were not just chosen by the gods, but a god incarnate. The one pharaoh who attempted to introduce monotheism failed pretty spectacularly. I’m sure there are more examples. I don’t think that only Christianity is going to provide a basis for some version of Divine Right.

I’ve often wondered if Constantine “converted” because he saw Christianity becoming more and more popular, and realized it wasn’t going anywhere but up and he might as well jump on and ride it as far as he could. I don’t know enough about the history of the time to know if that was likely or not, though.

Romulus was the god who protected the City of Rome, and by extension, the empire.

I do not wish to dance along the precipice of GQ rules, so let me just say that politics — as a system of manipulation for the purpose of acquiring power — has played a role in very many of history’s significant events. It has often been the case that leaders have chosen the path of greatest political expedience.

Thank you all for replying.
Thank you Lib, for the very literal event, which some dopers may not know. I did know that, but, as one can see from my question, I was indeed looking for an answer more consistent with the realpolitik mindset. That isn’t a slam, by the way, I truly value your contribution.
You do raise a very interesting point which I had not considered. The Pharaohs were quite assured within the system of divine right, nevertheless, they managed to do this within a polytheistic culture. Hmmmn, definitely something to think about.
I think the idea you express in your last paragraph, i.e. Christianity’s increasing popularity, is similar to my line of thinking. Not exact, mind you, just similar.
Perhaps we’ll never know, and I was looking for an historical interpretive answer, so I’m not sure where we go from here. Maybe I could ask a mod to move this if it ventures too far into the realm of opinion.


I explained how historians look to that “particular event”.
Salaam. A

I hope you aren’t taking it personal that I didn’t mention you by name. I did thank everyone for replying.
I haven’t had the time to follow up the various leads you, or anyone else for that matter, have given me. The question still intrigues me, and I’ll get to the bottom of it, just not right this minute.

Could Christianity’s evangelical nature have something to do with it?

Christianity is a religion that is designed to spread. Many other relgions are content to serve only a specific people. But Christianity encourages conversions. The Christian God is the God of all people, not just the Christians. As such, it is suited for creating a widening sphere of influence- exactly the sort of thing an empire would need.

Missionaries have long gone hand in hand with political conquest. And cultural domination is easier to maintain that military domination. Something about Christianity makes it easy to convert people too…I mean, people really are converted by Chick tracts. Nations with religious similarities tend to align politically and even seek a single leader- and an emperor would fit the bill nicely

Constantine surely was this potential, and realized that combining political power with a fast spreading religion was the way to go.

That’s an interesting thought even sven.

I notice you live (post from anyway) in Santa Cruz.
I go there a lot with my girlfriend. Maybe I’ll see you sometime.

I’ll note, for the record, that Maxentius Daia was extremely bigoted against Christians, and persecuted them within his domain.


No, I was just pointing out to you the historic


I was just pointing out the historical research about the whole story.

The question if Contantine became Christian and if yes: why, when and where he became Christian isn’t resolved.
Salaam. A

I only have an amateur interest in Byzantine/Late Roman history, and cannot compete against Aldebaran’s erudition (not that this is a competition!). But I have just finished Colin Thurbron’s factional treatment of Costantine’s campaign against Maxentius, “Emperor” and thought it pretty good. That touched upon the central issue of your OP, and if I understood it correctly suggested Constantine went with Christianity partly out of political expediency driven by the fact (fact?) that of the major religions Christianity was not only monotheistic but denied the existance of any other gods/religions. As such it had to grow and convert or die. If I understand correctly, other religions tolerated existance of other belief systems and were content to operate on the basis that “my god’s harder than your god”. The need for Christianity for conquest over other religions would then equate with Romes need to launch pre-emptive strikes against external threats. It would also give Christianity a staying power that other religions did not have in response to persecution.

As an aside I though Mithrites was the god of choice within the Roman army. I assume this differs from Sol Invictus, or is it another identical religion going under a different name? Googling has not helped me much here. In any event did not Christianity simply adopt a lot of the practises of the nearest rivals in order to co-opt their adherants all the easier???

Excuse the questions - as opposed to answers - it is just I feel I know a lot less than I thought I did on this subject 20 minutes ago.