Religion is a complex phenomenon, one that has many effects on a person’s worldview and behavior. It encompasses spiritual and supernatural components that impact one’s worldview, morality, culture, beliefs, and approach to certain writings or persons or places. The lines between religion and philosophy, tradition, myth, and even music are not easily drawn.

Many people have tried to define religion, often arguing that there is one thing that makes something religious: a belief in the existence of God. Others argue that religion is a response to an experience of the pervasive presence of powers outside human control, which impinge on human existence and radically relativize humans’ sense of self-sufficiency. Still others believe that there are some human activities that are intrinsically religious, such as caring for the sick and the needy.

Some scholars have taken a more formal approach to religion, seeking to categorize religious phenomena in terms of some measurable characteristics. Durkheim’s definition of religion in Elementary Forms of the Religious Life, written late in his career (1912) exemplifies this approach. In this view, a religion is whatever system of practices unites people into a moral community (whether or not those practices involve belief in any unusual realities).

Other scholars have rejected the idea that there is such a thing as a substantive definition of religion and have instead focused on the function that it plays in a person’s life. This functional view of religion is exemplified by the work of Paul Tillich, who defines religion as “any dominant concern that serves to organize a person’s values” (whether or not that concern involves belief in any unusual realities).

A third way to define religion is through a combination of both functional and substantive elements. This is the approach that is most prevalent in the contemporary literature, and it combines elements of both social and cultural definitions. In this view, a religion is defined as “a combination of social and ritual activities that help to bring about a sense of unity in the face of an apparently hostile environment.”

There is much debate about whether or not any of these definitions are valid. Some critics argue that the concept of religion is an invented category, and that its modern semantic expansion went hand in hand with European colonialism. Others cite research showing that there are some benefits to being religious, including reduced risk of stressful life events (like divorce or separation, financial stress, crime, and venereal disease), increased morality, and more self-control.

Whatever definition is ultimately used, it is clear that the study of religion is a fascinating and important endeavor, with far-reaching consequences. People who take the time to understand the complexity of this phenomenon will be better able to appreciate its significance in their lives and that of the people around them. And they will be better positioned to respond effectively when the social or psychological effects of religion are challenged by adversity, science, or modern ideas about what constitutes a religion.