The pagan Roman Empire was the most complex and refined civilization that had ever appeared on earth. Its religious practice ensured eternal protection by the gods. Its emperor was appointed by the divinity as ruler of the Roman state. Although the empire flourished for many centuries, its religious system did not. The Roman Empire Christianized under Constantine, and this new reality created a new Christian self-concept: imperial Christianity. The Christianization of the empire proved the triumph of Christianity over all its religious competitors and demonstrated that God loved the church and its mighty kingdom.
This new and improved Roman Empire was called the Byzantine Empire, and its Christian emperor became known as God's regent on earth.