This book examines how enlightened Scottish social theorists c.1740 to c.1800 understood the origin and development of religion. Challenging scholarly disregard for the topic, it shows how most prominent thinkers of the Scottish Enlightenment thought deeply about the relationship between religion, human nature and historical change. The Scots viewed this relationship as an important strand within the study of the 'science of human nature' and the 'history of man.' The fruits of this investigation were a sophisticated and innovative account of religious change that is characterized by a striking modernity and naturalism, even by the more devout theorists. The views of the surveyed here need to be incorporated into our larger histories of the 'science of religion' as much as they do into our understanding of the social theory of the Scottish Enlightenment.