Religion is a complex and controversial subject, spanning disciplines as diverse as anthropology, history, philosophy, theology, religious studies, sociology, psychology, and cognitive science. It is even a subject of intense debate within the field of religious studies, with scholars of different approaches arguing for their position on how best to study it. Some of these approaches are substantive and some are functional; some take a formal approach, looking for a structure that will help them classify facts about religion; others use a prototype approach, in which they try to identify the things that people first think of when they hear the word.
Substantive definitions of religion typically focus on beliefs about supernatural entities and cosmological orders. These definitions have a long history, going back at least to the Greek philosopher Xenophanes. Anthropologists and ethnographers have also contributed to the understanding of what counts as a religion, as they have studied many cultures, including those of primitive peoples.
The emergence of the social sciences has allowed scholars to make more systematic observations about cultures throughout the world. This, in turn, has fed into the development of theories about the nature and origin of religion. Some of these theories are based on empirical observation, while others are based on more abstract and theoretical explanations about why and how religion develops.
Early sociological functionalists like Emile Durkheim defined religion as any system of practices that unite a group into a moral community, whether or not the members believe in unusual realities. This definition still has a good deal of currency, though it is sometimes criticized by critics who argue that it is too narrow and excludes from the category all forms of group association that do not involve belief in gods or spirits.
More recently, functionalists have begun to focus on the functions that religions serve in societies. These have included the functions of providing comfort and support during times of distress, helping people feel part of a larger group, and providing meaning and purpose in life. Some studies have even found that religiosity leads to better health and longevity.
As a result of these and other developments, there are now functionalists of all kinds in the social sciences, with a great variety of approaches to the study of religion. Psychologists and neuroscientists, for example, have begun to think about the function of religion by looking at how it fulfills psychological needs in humans.
Other scientists, such as anthropologists and historians, have developed more traditional theories of religion by analyzing the ways that particular cultures have practiced their faiths over time. They have also studied the ways that cultural practices, such as myths and rituals, are passed down from generation to generation. This work has helped to clarify the distinction between what is and is not a religion, as well as to show that some religious traditions are more similar to one another than to other cultural practices. In addition, anthropologists have made it possible for us to understand that there are religions in the world that do not believe in disembodied spirits or in an afterlife.