Religion is universal across human societies and this chapter reviews the earliest evidence of spiritual belief from the fossil and archaeological record. Religions have very specific roles in societies, depending on the complexity and institutional structures of the society, and this chapter explores the ways these roles have shifted over the course of the last 5,000 years. In particular, it discusses the institutional relationships, such as those seen in the use of sacred knowledge and authority, that characterize the interrelationship between government and religion, seen in such diverse states ranging from ancient Egypt to pre-war Japan. It discusses the transitions from polytheism to monotheism, especially in the light of Hume’s hypotheses on the evolution of religion, but also noting that polytheism is alive and well in modern Hinduism. Finally, it discusses the appearance of alternatives to religion, emphasizing the appearance of science during the Enlightenment as a viable alternative for knowledge about the material world, but also reviewing more philosophical critiques; contrasting, for example, Descartes with Hume, but also reviewing Marx and Freud.