Constantine was a good soldier. His father was the emperor of the Western Side of Rome.
The Edict of Milan
In 306 Constantine I became emperor since his father died. But it wasn't easy. He had to defeat his enemy Maxentius in 312 in the Battle of Milvian Bridge. To commorate this event, he built the Arch of Constantine.
Council of Nicaea and the Nicene Creed
According to legend, in the Battle of the Milvian Bridge, Constantine saw a cross in the sky and the Latin words "in hoc signo vinces" inscribed on the cross, which means "In this sign you shall conquer". Constantine also had a dream where he saw the words Chi and Rho" which means "Christos", or Christ.
Constantine, Ruler of Rome
After these spiritual experiences, Constantine decided to sign the Edict of Milan in 313. The Edict of Milan states no Christian will be persecuted and Christians are free to worship God!
Constantine I did a lot of other great things. He formed the Council of Nicaea, which had 300 bishops and church leaders. They discussed differences and even made the Nicene Creed, which states "Jesus is God".
Though there were a few mishaps here and there, Constantine proved as a religious and great ruler who will be remembered for decades.