Throughout history scholars have tried to pin down what religion is. Some have focused on the beliefs held by believers, others on the practices associated with those beliefs, and still others on the institutions that support those beliefs. Most attempts have been “monothetic” in that they assume that every instance of a concept will have one defining property, but the last several decades have seen a growing trend towards “polythetic” approaches.
A polythetic approach tries to avoid the idea that an evolving social category has an ahistorical essence, and so it looks for a variety of properties that might be found across religions, or at least among most religious groups. For example, it might include an emphasis on moral conduct or on the importance of faith in a higher power. It might include the notion that a religion is founded on a particular book or text, or that it teaches a specific set of values. It might also take into account that a religion is rooted in a specific group of people, or that it reflects the cultural or historical context of its adherents.
Many sociologists and anthropologists adopt this approach. For example, Emile Durkheim defined religion as whatever system of practices unites people into a single moral community (whether or not that system involves belief in unusual realities). Others have looked for the significance that a religion has in an individual’s life, or at the role it plays in society.