君士坦丁也被称为君士坦丁一世皇帝或君士坦丁，在米兰法令中颁布了对基督徒的宽容大法，召集了一个全基督教委员会讨论基督教教义和异端，并在其新首都（拜占庭/君士坦丁堡，现伊斯坦布尔）修建了基督教大厦

君士坦丁是基督徒吗？

简短的回答是，“是的，君士坦丁是基督教徒，”或者似乎说他是基督教徒，但这掩盖了问题的复杂性。君士坦丁在成为皇帝之前可能就是基督徒[对于这个理论，请阅读T。G艾略特；菲尼克斯，第41卷，第4期（1987年冬天），第420-438页]他可能自312年在米尔维安桥赢得战斗以来一直是基督徒，尽管一年后随附的展示他与太阳神不可侵犯的奖章提出了问题。传说中，君士坦丁在基督教的象征上有一个十字架，上面写着“在特别的文森斯签名”的愿景，这使他承诺，如果获得胜利，他将信守基督教。

古代历史学家论君士坦丁的皈依

尤西比乌斯是君士坦丁的同代人，也是基督教徒，于314年成为凯撒利亚的主教。尤西比乌斯描述了一系列事件：

第二十八章

"How, while he was praying, God sent him a Vision of a Cross of Light in the Heavens at Mid-day, with an Inscription admonishing him to conquer by that. ACCORDINGLY he called on him with earnest prayer and supplications that he would reveal to him who he was, and stretch forth his right hand to help him in his present difficulties. And while he was thus praying with fervent entreaty, a most marvelous sign appeared to him from heaven, the account of which it might have been hard to believe had it been related by any other person. But since the victorious emperor himself long afterwards declared it to the writer of this history, (1) when he was honored with his acquaintance and society, and confirmed his statement by an oath, who could hesitate to accredit the relation, especially since the testimony of after- time has established its truth? He said that about noon, when the day was already beginning to decline, he saw with his own eyes the trophy of a cross of light in the heavens, above the sun, and bearing the inscription, CONQUER BY THIS. At this sight he himself was struck with amazement, and his whole army also, which followed him on this expedition, and witnessed the miracle."

第二十九章

"How the Christ of God appeared to him in his Sleep, and commanded him to use in his Wars a Standard made in the Form of the Cross. He said, moreover, that he doubted within himself what the import of this apparition could be. And while he continued to ponder and reason on its meaning, night suddenly came on; then in his sleep the Christ of God appeared to him with the same sign which he had seen in the heavens, and commanded him to make a likeness of that sign which he had seen in the heavens, and to use it as a safeguard in all engagements with his enemies."

第三十章

"The Making of the Standard of the Cross. AT dawn of day he arose, and communicated the marvel to his friends: and then, calling together the workers in gold and precious stones, he sat in the midst of them, and described to them the figure of the sign he had seen, bidding them represent it in gold and precious stones. And this representation I myself have had an opportunity of seeing."

第三十一章

“对十字架标准的描述，罗马人现在称之为拉巴鲁姆。现在它是按照以下方式制作的。一支长矛，上面覆盖着黄金，通过在其上放置横杆形成十字架的形状。顶上镶嵌着黄金和宝石的花环；在这里面，是救世主名字的象征，两个字母通过其首字母表示基督的名字，字母P在其中心与X相交：这些字母是后来皇帝戴在头盔上的习惯。长矛的横杆上悬挂着一块布，这是一块皇室的布，上面绣着大量最耀眼的宝石；它也与黄金交织在一起，给观看者带来了难以形容的美丽。这面旗子是方形的，竖直的旗杆下部很长，上面有一幅虔诚的皇帝和他的孩子们的金半身像，在十字架的奖杯下面，皇帝不断地利用这一拯救的标志作为抵御一切敌对势力的保障，并命令其他类似的标志应在他的所有军队中处于领先地位。”凯撒利亚的尤西比乌斯受祝福的君士坦丁皇帝的一生

为什么君士坦丁信奉这个信仰

五世纪历史学家佐西莫斯（Zosimus）写道，君士坦丁似乎信奉新的信仰，这是出于务实的原因：

" Constantine under pretence of comforting her, applied a remedy worse than the disease. For causing a bath to be heated to an extraordinary degree, he shut up Fausta [Constantine's wife] in it, and a short time after took her out dead. Of which his conscience accusing him, as also of violating his oath, he went to the priests to be purified from his crimes. But they told him, that there was no kind of lustration that was sufficient to clear him of such enormities. A Spaniard, named Aegyptius, very familiar with the court-ladies, being at Rome, happened to fall into converse with Constantine, and assured him, that the Christian doctrine would teach him how to cleanse himself from all his offences, and that they who received it were immediately absolved from all their sins. Constantine had no sooner heard this than he easily believed what was told him, and forsaking the rites of his country, received those which Aegyptius offered him; and for the first instance of his impiety, suspected the truth of divination. For since many fortunate occurrences had been thereby predicted to him, and really had happened according to such prediction, he was afraid that others might be told something which should fall out to his misfortune ; and for that reason applied himself to the abolishing of the practice. And on a particular festival, when the army was to go up to the Capitol, he very indecently reproached the solemnity, and treading the holy ceremonies, as it were, under his feet, incurred the hatred of the senate and people." THE HISTORY OF COUNT ZOSIMUS. London: Green and Chaplin (1814)

可能在临终前改变了信仰

君士坦丁在临终受洗之前可能不是基督徒。君士坦丁的基督教母亲圣赫勒拿（St.Helena）可能改变了君士坦丁的信仰，也可能是君士坦丁改变了她的信仰。大多数人认为康斯坦丁是312从米尔维安桥来的基督徒，但直到四分之一世纪后他才被洗礼。今天，根据你所信仰的基督教的哪个分支和教派，君士坦丁在没有洗礼的情况下可能算不上基督徒，但在基督教的最初几个世纪里，当基督教教条尚未确定时，这并不是一个明确的事件。

为什么他等了这么久才接受洗礼

以下是古代/古典历史论坛的一些回应。请将您的意见添加到论坛帖子中。

君士坦丁临终前的皈依是道德实用主义者的行为吗？

"Constantine was enough of a Christian to wait until his deathbed to be baptized. He knew that a ruler had to do things that were against Christian teachings, so he waited until he no longer had to do such things. That may be the thing that I most respect him for." Kirk Johnson

或

君士坦丁是个口是心非的伪君子吗？

"If I believe in the Christian god, but know that I will have to do things which are against the teachings of that faith, I can be excused for doing so by postponing baptism? Yes, I'll join Alcoholics Anonymous after this crate of beer. If that isn't duplicity and subscription to double standards, then nothing is." ROBINPFEIFER

见Robert M。授予《宗教杂志》，第55卷，第1期（1975年1月），第1-12页