Religion is a collection of cultural traditions that focus on the supernatural, and it typically involves beliefs in one or more gods or spirits. It can also involve worship, rituals, and moral guidance. Religions are commonly identified with certain geographic areas or a particular historical period, and they are often linked to specific texts or events. In more humanistic or naturalistic forms of religion, the spiritual and moral concerns that are central to many faiths may be expressed in terms of people’s relationships with or attitudes toward the broader human community or the natural world.

The idea of religion has been subject to much debate over the years. Some scholars have argued that the concept is an abstract term, while others have defended its concreteness. Regardless of how the term is defined, though, scientific studies have found that religion is associated with certain positive health outcomes. These benefits include a sense of purpose and belonging, social connections, and improved mental wellness.

Traditionally, most attempts to analyze the nature of religion have focused on its beliefs or its practices. These approaches have been called “substantive” because they define membership in the category based on the presence of some sort of belief in a distinctive kind of reality. Emile Durkheim, for example, defined religion as whatever system of practices unites a number of people into a moral community (whether or not those practices involve belief in any unusual realities). In the twentieth century, however, there was an emergence of an importantly different approach to the question of religion: a functional definition. This one dropped the requirement that religions believe in something special and instead defined it as any group of practices that organizes a community into a moral unit (whether or not these groups have beliefs in unusual realities).

While the vast majority of modern religious believers still rely on some form of this functional definition, there is a growing movement to reject the idea that a thing can be defined by the fact that it is a “religion.” Some of those who take this position advocate for an even more radical change: namely, that we should stop treating the term “religion” as if it has a necessary and sufficient definition.

For the purposes of this article, we will adopt the latter position. While we will continue to use the term “religion” in its conventional sense, it is crucial to recognize that there are a number of alternative ways for defining a group of social practices. The most promising of these alternatives is that we should treat the notion of a religion as a family resemblance concept, and not as one that has essential properties. This will allow us to more easily identify the kinds of practices that can be classified as a religion and that can benefit from the kinds of research that are being done on them. It will also permit us to consider new ideas about how to improve them.