Religion is a complex aspect of human culture and one that is present in all cultures. Yet, it is not a universal phenomenon and it can be defined substantively or functionally in ways that are not necessarily pan-human. For example, in the latter case where religion is defined as beliefs and practices that generate social cohesion or as those that provide orientation in life, then any movement that fits that definition would be considered a religion. This is a way of using the term that is not necessarily true and it can lead to conclusions about religion that are unfounded.
A major early work on the sociology of religion was that by Emile Durkheim, who used a functional definition and believed that any belief system with a large enough committed group could be deemed a religion. He also believed that religion had beneficial functions for society, such as socialization, generating solidarity, and promoting morality. He saw that it reduced the incidence of some social pathologies, such as out-of-wedlock births and crime, and helped people live their lives more meaningfully.
Other approaches to the study of religion have been more substantive, such as those by Paul Tillich and Sigmund Freud. However, a number of scholars object to the substantive definitions because they feel that they are too broad and inclusive and that they make it impossible to measure or understand the growth, decline, or impact of religion. These scholars have argued that the proper role of the sociologist is to uncover what makes something a religion through empirical research rather than to try to construct a definition that is objectively valid.