Religion involves engaging with postulated superhuman powers through complexes of prescribed practices in hopes of realizing human goods and avoiding human bads. It may also include ecstatic experiences of the divine and fellowship among believers. It can also involve beliefs about the existence of a supreme being or gods, and a variety of ways that humans express religious faith and belief through ritual, art, music, dietary restrictions, dress, symbols, and other cultural means.

Historically, scholars have used various definitions of religion to distinguish it from other types of belief and behavior. For example, they have distinguished between a monotheistic or polytheistic religion and nonreligious beliefs and practices. They have also compared religions to each other in order to understand them. This approach was aided by the discovery of new regions and cultures, which opened up the study of ancient mythology and religion to a wider audience.

Some critics of the concept of religion have argued that it is an entirely invented category, and that it should not be applied to anything other than its own historical and cultural context. They claim that the modern semantic expansion of the term religion went hand in hand with European colonialism, and that people should stop treating it as if it corresponded to something that existed outside this sphere.

Other critics have taken this argument further, and argued that the very fact that there are multiple definitions of religion reveals its socially constructed nature. They have criticized the tendency to focus on the cultural and historical context of the development of the term as a way of ignoring its functional character, and have argued that this functionalism explains the ubiquity of religions throughout history.