I. When the Roman general Constantine became Emperor in 312 AD, the Church entered a new era. The following year the Edict of Milan was signed which officially ended the persecutions and the peoples of the Empire, especially Christians, were given the freedom to practice their religion. Constantine showed his support for Christianity by the following: building basilicas for worship, backing the production of Bibles, and restoring land that had been taken away from Christians during the persecutions. Constantine also gave the Bishop of Rome, the Pope, the Lateran Palace.
II. In 318 AD a priest named Arius taught and preached that Jesus, though the Son of God, was created - meaning He did not exist from the beginning. The Church on the other hand taught that Jesus was never created, but existed from the beginning of time. To defend the Church's position and defeat this new heresy, named Arianism, the Church called for an ecumenical council.
III. To effectively deal with the Arian heresy, which many Bishops embraced, the Church in 325 AD called over two hundred Bishops together to open the Church's first ecumenical council in Nicea. Although the vast majority of the Bishops were from the East, several attended from the West including papal legates who represented Pope Sylvester. The Council's greatest achievement was the condemnation of Arianism and the development of the Nicene Creed, which we still recite today.
IV. One saint that stands out during this century is Athanasius (297-373). St. Athanasius, Bishop of Alexandria, was the staunchest defender of the Nicene Council. His support for the teachings of the Council, especially in relation to Arianism, forced him into exile a total of five times by numerous Bishops who supported Arius and his teaching.
V. In the later part of the century, a tribe of barbarians called the Goths crossed the German Danube River and entered the Roman Empire. This would eventually lead to the Empire's collapse.