Religion is a unified system of ideas and beliefs that offers its followers a focus for their devotion, a code of moral conduct, and an understanding of themselves and the world around them. It is often associated with a transcendent power or god and usually involves a belief in a afterlife. Its followers strive to live a good and fulfilling life based on the moral teachings of their religion and avoid bad habits such as drug abuse, out-of-wedlock births, and stealing. In its most general form, religion provides a set of goals that can be achieved in this life (a wiser and more productive, charitable, and successful way of living) or in the process of rebirth and reincarnation.

A large number of people worldwide are religious, including 47% of adults in the United States. Religious affiliation is largely a product of the parents and cultural environment in which one is raised. People are also compelled to belong to a religious organization by the desire for social connection and the human need to feel that they are part of something larger than themselves.

There are critics of religion that have argued that the concept is an invention and that the assumptions baked into it have distorted our grasp of historical reality. Others, like George Herbert Mead, have argued that the term is useful in describing how societies organize themselves. They have advocated a “functional” definition of religion that drops the substantive element and defines it as whatever system of practices unites a group of people into a single moral community.