Islam has played an important on-going part in the history of Christianity and the world as a whole even up to the present day. It behooves the Catholic home school child to be aware of the role Islam has played in world history, the true nature of the Crusades, and the contrast between Christianity and Islam. The Bible and the Qur'an presents the profound differences between Christian Scripture and the Islamic sacred texts. Inside Islam: A Guide for Catholics - 100 Questions and Answers gives us a look inside what will soon be the largest religious group in the world. Hilare Belloc analyzes Islam as a heresy in The Great Heresies. For an understanding of the crusades try What Were the Crusades? 3rd Edition and/or The Crusaders: The Struggle for the Holy Land.  An intriguing novel, Crusader King: A Novel of Baldwin IV and the Crusades, tells the story of the last Crusader King in Jerusalem. He was beset not only by the Moslems but also by treacherous Christians and by leprosy.