What is the relationship between Constantine and The spread of Christianity?

Constantine the Great played a pivotal role in the spread of Christianity by becoming the first Roman emperor to convert to the faith. His Edict of Milan in 313 AD granted religious tolerance to Christians and allowed them to worship freely, significantly reducing persecution. Constantine also supported the Church through the construction of major basilicas and the convening of the First Council of Nicaea, which helped unify Christian doctrine. His endorsement of Christianity helped it transition from a marginalized sect to a dominant religion within the Roman Empire.