Yes, but the Islamic religion was not opposed to Christianity. In fact, as one of three great religions “of the book,” Islam had much in common with Christianity, as well as Judaism. Its doctrine included a belief in one God, the importance of prayer, the idea of a church or brotherhood for all members of the religion, and the obligation to care for the poor. What was distinctive about Islam, in comparison to Christianity, was its rejection of the idea of the Catholic Trinity, requirements of fasting and other forms of bodily purification on holy days, and the necessity for every Muslim follower to make at least one journey or pilgrimage to Mecca. The continual importance of God and homage to Old Testament prophets was shared with Judaism, although, unlike Judaism, Islam had a positive conception of Heaven.