Religion is a unified system of thoughts, feelings, and actions that unites people in a community. It is a belief in something or someone sacred, such as a god or spiritual concept, and it is often accompanied by a code of conduct that governs the behavior of its followers. It is a belief that there are forces or powers beyond the control of humans, and it is also an expression of hope in these supernatural or spiritual forces. It is a belief that there is a purpose to human life and that this purpose is known through a relationship with the divine.

It has been argued that religious beliefs evolved out of human curiosity about the universe and about life and death, as well as out of fear of forces that are beyond their control. These fears led to the desire for a good fate and an afterlife, and they were later converted into hope in the form of a god or spirit that watches over humanity and has the power to help them. The various religions in the world differ from one another, but all of them share similar characteristics. They include a belief in something or someone sacred, a code of conduct and a moral philosophy that sets standards for judging one’s personal actions and the actions of others.

The classical approach to defining religion relies on substantive definitions that determine whether an object falls into the category of religion. For example, Emile Durkheim defined religion as whatever practices unite a group of people into a single moral community (whether or not these practices involve belief in any unusual realities). Clifford Geertz likewise used a functional approach in his definition of religion, though some scholars have challenged the extent to which his definition is truly a functionalist one (see Hervieu-Leger 1987 on “quasi-religions”).

These functional and substantive approaches are still useful, but they leave out an important dimension. If a person defines something as “religious” only if it meets certain criteria, it is possible that he or she will miss some forms of religious activity that are important for the health of his or her society. For this reason, some scholars have developed “polythetic” definitions of religion that take advantage of Ludwig Wittgenstein’s notion of family resemblance.

Polythetic definitions of religion ask how many crisscrossing and partially overlapping features are shared by the objects that have been designated as religious. These types of definitions have been helpful in identifying the enduring themes that are present in all religions. They have also helped scholars to distinguish between religious traditions that may appear very different from one another.