Religious ideas and practices vary widely among people. They often share certain features, such as devotion to a supreme deity or gods. They can also be intensely personal and may involve emotional and psychological states, including feelings of oneness with others or trancelike conditions. These experiences can be deeply moving and transformative for believers. Religion can also serve several functions: it provides meaning and purpose to life, reinforces social stability and unity, serves as a source of power and control, promotes physical well-being, and encourages action to bring about positive social change.
Sociologists use the concept of religion to sort out human activities, beliefs and phenomena that vary widely across cultures. They consider whether a particular activity is religious and, if so, what it is about the activity that qualifies it as a religion. They also explore the historical evolution of the notion of religion and how its semantic range has shifted over time.
The earliest attempts to understand the concept of religion used “substantive” definitions that determined membership in a category based on belief in a unique kind of reality. Emile Durkheim, for example, defined religion as whatever system of practices united a group of people into a moral community. More recent sociologists have moved away from this view of religion to focus on the functions it can perform.
Many scholars adopt what is known as a “polythetic” approach to understanding the concept of religion. Polythetic definitions avoid the claim that a social category has an ahistorical essence, but they still recognize that some properties are common or even prototypical of religions.