This book presents a detailed explanation of the classical Islamic concept of God's unity as it relates to faith and acts of religious devotion. It also discusses the major areas within which the Islamic Unitarian belief (Tawheed) is either nullified or compromised by idolatrous concepts collectively called the Shirk. The uniqueness of this work lies not only in its thorough treatment of the subject in a fluid and uncomplicated English style but also in its modern presentation of classical theological issues.