In his zeal to convert Muslims to Christianity, Zwemer was unmatched and this book helps to explain why. Not shy about admitting that the three major monotheistic religions share the concept of one God, he begins an examination of Islamic ideas about God, from a Christian perspective. Starting with the premise of the singularity of Allah, Zwemer discusses the Muslim ideas of the divine essence. In a chapter about the ninety-nine names of Allah he explores the similarity to the rosary and Islamic ideas of divine justice. Passing next to the attributes of Allah, Zwemer examines and analyzes what Muslims assert regarding God. In further chapters he deals with how Allah interacts with the world, the concept of the Trinity, and predestination. Determining that the completed idea of God in Islam is incomplete, Zwemer concludes with a case for the God of Christianity.

Samuel Marinus Zwemer (1867-1952) was an American missionary to Islamic regions. He studied at Hope College in Michigan and New Brunswick Theological Seminary in New Jersey. He traveled to the Middle East to attempt to convert Muslims to Christianity. He taught at Princeton Theological Seminary.