Religion is the term for human beings’ relation to that which they deem to be holy, sacred, divine, absolute, spiritual, or worthy of especial reverence. It is also the means by which people deal with their ultimate concerns, such as their place in the world, what happens to them after death, and the nature of reality. These beliefs and practices can be extremely varied. They can be large-scale and coherently organized, with a clear hierarchy of popes, cardinals, bishops, priests, laity, men’s religious orders, women’s religious orders, etc., or they can be loosely organized and even devoid of any structure at all, such as Hinduism.

In its various forms, religion is a fundamental element in the lives of two-thirds of the world’s population. It is an important source of moral and ethical principles that guide many of the most important aspects of life, such as marriage, family, business, government, education, and even science.

It has also been the origin of some of the most powerful social movements and ideas in history. It has been responsible for abolition of slavery, the spread of democracy, and the expansion of scientific research into cultures around the globe. But religion also can be the source of intolerance, cruelty, bigotry, social oppression, and self-opinionated nastiness. It has been the motivation for wars, civil rights violations, and violence motivated by differences in belief.

Those who study religion try to understand how this broad range of phenomena works. Traditionally, scholars have sought to define the concept by identifying its necessary and sufficient properties, but this approach has come under attack in recent times. A growing number of people have opted for “polythetic” definitions that recognize more than one property as characteristic of religion. These approaches help to avoid the claim that a social category has an ahistorical essence.

This move toward a polythetic understanding of the religions was initiated by Emile Durkheim, who stressed that it is the functions that a system of beliefs and practices plays for a society that make it a religion, rather than the beliefs themselves. Durkheim’s work remains a cornerstone of sociological thinking about religion today.

A further point about the polythetic definitions of religion is that they all recognize a core set of properties that are shared by all religions. This core includes beliefs in a supreme being, a creator God or gods, and a plan for the universe. This definition is similar to that of science, which has a core set of common properties shared by all scientific theories. While some scholars believe that defining the concepts of science and religion in this way is an artificial and dangerous separation, it remains an essential part of the intellectual tradition. This is because it allows scientists to look at these two domains independently and critically, a critical step in the effort to create a better world. Without the separation of science and religion, there is a danger that purely secular approaches will be used in public policy, psychotherapy, or even the classroom, to the detriment of both.