Christianity is a monotheistic religion based on the life and teachings of Jesus Christ. Some key beliefs include belief in God the Father, Jesus as the Son of God, and the Holy Spirit. A major turning point was Constantine's conversion, which ended persecution of Christians and established Christianity in the Roman Empire. Christian art expresses emotions related to the Christian faith through depictions of Bible stories and subjects. Early Christian art included symbolic images in catacombs and representations became more naturalistic over time as styles evolved.