Religion provides meaning and purpose in life, gives a sense of stability and belonging, serves as an agent of social control, reinforces social norms and values, reduces psychological and physical stress, and may motivate people to work for positive social change. These functions – and many others – are of great importance to individuals, families, communities, states and nations.

Religious significance varies greatly and is highly personal. Religious beliefs and practices can take many forms, from a belief in a supreme being or god to a set of moral rules that govern how we should behave. Religions often involve rituals and ceremonies that may be intense, sometimes involving crying, laughing, screaming, or trancelike conditions, or they can be relatively simple.

Whether they are complex and organized, with a central authority or church, priests, sacred texts, and a hierarchy of leadership, or rudimentary and unorganized, with no clear leader, all religions serve certain essential functions that make them a part of human society. The three main nineteenth century European sociologists who focused on religion – Karl Marx, Emile Durkheim and Max Weber – stressed these functions in their analyses of the role of religion.

They also stressed that beliefs and practices can only be considered to be religions if they are given special significance by members of a group. This is called a functional definition of religion, and it makes it possible to study all the various ways in which humans organize their lives in terms of beliefs that are given significance by some group or another.