This work reviews the main theories which have been put forward to account for the origin and nature of religion, and covers both empirical (sociological, anthropological and psychological) theories and religious theories (revelation, religious experience, mysticism, etc.). It looks at the question "Why theories of religion?". The book provides an analysis of the earliest theories found in the Western tradition (ancient Greece and Rome) and then thematically traces these right through to contemporary debates, engaging with the main figures in this debate including Frazer, Feuerbach, Jung, Hegal, etc.