Answer:
Constantine was the first and only ruler to stick to the Christian religion. He released an edict defending Christians in the kingdom and converting them to Catholicism on his death's doorstep in 337.
It is feasible (but not certain) that somehow Constantine 's mother, Helena, had directly exposed him towards Christianity; in any scenario, he had only proclaimed oneself a Christian after authorising the edict of nantes. Trying to write to the Christians, Constantine made it very clear that he assumed that he alone obliged to pay his achievements to the safety of the supreme deity.
Some of the alleged watersheds of civilization is the 'conversion' of Emperor Constantine to Christianity in or around AD 312. Historians were shocked at this notion. Historically, the emperors were aggressive or disrespectful to Christians. There are two records of the transition of Constantine to catholicism. The first one is Lactantius, a mentor to Constantine 's friend, and a strong authority. They states that in Gaul, before they set off to Rome, Constantine as well as his troops saw a huge cross in the atmosphere.