Augustine of Hippo is baptized on Easter Eve.
Augustine converts to Christianity at the age of 32 and will become one of the most prominent theologians in the entire history of the Christianity. His books City of God and Confessions will deeply influence Christians for centuries to come.
After flirting with Manicheism he converts to his mother's religion, Christianity, and then founds a small monastic community in North Africa. He will be elected Bishop of Hippo because this is still a time when people have a voice in who gets to lead their religious communities and institutions.
Augustine of Hippo probably becomes most widely known for developing the doctrine of original sin. This doctrine stands opposed to Pelagianism, which is a bit more optimistic. Augustine believes humans are by nature sinful creatures who are unable to lead a sinless life.