What differences does the author point out between Christianity and Islam in the second section of "Down at the Cross"?

Baldwin compares the Nation of Islam preachers, and Elijah Muhammad in particular, with the preachers he listened to when he was a child, and considers the differences between the Christian belief system and that of the version of Islam practiced by Elijah Muhammad and his followers. The principle difference is that the Christian God is considered white, while the Muslim God is considered black.