Potemkin wrote:No doubt Constantine was sincere in his conversion to Christianity (though I note that he only agreed to be baptised on his deathbed, once he had already committed all his sins), and I also have no doubt that he really did see a vision of a giant cross at the Battle of the Milvian Bridge (though no-one else seemed to remember seeing it, lol).
I understand exactly where you are coming from and as always this is always where the problem lies. Western historiography has not bothered to understand either a) the relationship between the Greeks, Romans, Jews, Thracians, Persians, Germanics or more importantly b) the relationship of the Greeks(more specifically) with religion, God and cults.
The analysis of the events has relied on the polemics and panegyrics of the time but noone has bothered on actually making a true anthropological analysis by trying to comprehend the relationship of people with cults(over 1500 of them) during the time or the process with which someone declared that cult as affiliated with them.
A Greek person was expected and proactively encouraged to join at least 10 religious cults/societies/brotherhoods over his lifetime and the foreigner the better. A Greek person would join Thracian cults, Persian, Indian, Jewish, Germanic, Buddhist and at least another 6 local ones. Greeks spent copious amount of money sending their youth to be educated by great people and to be initiated in great mysteries(foreign and Greek). They had turned this into an industry since at least Plato and Pythagoras who popularised it, by the time of Constantine, this system had been developed to the extremes of absurdity and by parochial elite Romans to the extremes of kitschness as well.
This is something that you need to put into perspective, and also you need to understand the relationship of the Greeks with the Priesthood, to be a priest was a high honour for a Greek person and rich people would pay immense amount of money just to be the Priest of the Festival, that is the lead presenter of the festivities, that is how sponsorships came to be.
Greek Christianity organised and democratised a permanent priesthood that stabilised the post. Greeks flooded christianity for many social reasons and with great ease, when they had a permanent network in place they did what any other human/corporation in their place would have done, turn it into a monopoly.
Constantine never was 'baptised' mate not even on his death bed, but he was Christian and had been initiated in the religion, nor did he ever see "a vision", because Constantine had no such concept, as far as he was concerned he had already been initiated and his Christian works speak for themselves anyway.
You have simply fallen to the christian narrative and its antecedents, who simply cannot digest that the first Christian emperor was not baptised but was actually Christian, because they prefer to tell you a lie than bother explaining the complicated truth(which most people will not understand anyway). That at the time, Constantine had been initiated to cults from India to Ireland and one of those cults was also Christianity.
On top of that, there are more layers of nonsense that have been added by "enlightened" westerners who then wrote their own polemics or panegyrics simply piling up on errors.
But I also have no doubt that he was making a hard-headed political decision, to harness the religious sensibilities of a third of the population of the Roman Empire behind his dynastic ambitions. And yes, I think there was a certain element of "throwing in the towel", since he was the first emperor who was sensible enough to realise that attempting to eradicate Christianity was a quixotic and wasteful enterprise. It was better to harness it.
The reason you think "he threw the towel" is because you cannot see the world through Constantine's eyes, you can only see them through your own. I can assure you that at no point did that thought even pass from his mind.
The secularism of the time cannot be fathomed because it is being rationalised by people whose secularism is profoundly anti-religious and still in its infant stage. We 've had urban secularism for a few decades, perhaps a century depending where you are.
Greco-Roman people in Constantine's time had ultra-secular society for at least 8 centuries before Constantine while their secularism and religiosity were of a different kind than it is for people today. There are 700 years between Plato and Constantine, 700 years of uninterrupted city-building and unhindered propagation of ultra-secularism, cultism and all their baggage. Not 20-30 or 50 years as most people imagine the timing gaps in the antiquity. We 've had 30 years of Sagan and most people think "we 've been enlightened". The contradictions, fake news, post-truths, post-modernism, hippies, yippies, even trans, in their own variations had already happened by the time of Constantine.
There are several things that are simply out of perspective.
EN EL ED EM ON
...take your common sense with you, and leave your prejudices behind...