Religion is a large and diverse category of practices that people believe are spiritual. It is widely used today to categorize a wide variety of practices, the most familiar examples being Judaism, Christianity, Islam, Hinduism, Buddhism, Confucianism, and Daoism. It is also often used to describe a range of beliefs centered on a single symbol, such as the Native American totem or the New Age Movement, and to categorize eclectic belief-based movements. It is important to recognize that the concept of religion is not an objective thing; it is a social taxon that has evolved in response to certain needs and concerns of observers, and that its semantic range has grown since it was first categorized by anthropologists.

The earliest religious belief systems appear to have emerged from human curiosity about the world and the fear of uncontrollable forces. Many scholars suggest that these questions and fears led to the desire for immortality, for a loving creator who would watch over humans, and for an ultimate meaning in life.

Early religious movements typically incorporated these spiritual beliefs with rituals and a community of believers who shared similar beliefs and behaviors, as reflected in the phrase nobis religio, “our way of worship.” Religious communities frequently developed moral codes that dictated appropriate and inappropriate behavior. They also enshrined myths that explained the origin of the world and told stories about gods and goddesses.

Over time, some religious beliefs and practices changed in response to changes in the world around them, but others remained essentially unchanged for thousands of years. These changes and continuities led to the classification of a variety of religions as different branches of the same tree, and they are characterized by some common features:

In the nineteenth century, scholars began to develop theories of how religions developed that based on social and cultural factors. Anthropologists and sociologists, for example, analyzed patterns of social organization, craft specialization, political hierarchy, and kin-based groups, and they looked at the role of these organizations in creating religions.

Psychologists and neuroscientists, meanwhile, argued that religions are driven by emotional and psychological needs, such as a need to avoid death or to find purpose in one’s life. This view is sometimes referred to as the faith-based theory of religion.

Other scholars have developed functional definitions of religion, such as Emile Durkheim’s (1912) version, in which the term “religion” refers to whatever system of practices unite a group of people into a moral community (whether or not they involve belief in unusual realities). This view is sometimes referred to as the pan-human theory of religion. Regardless of the approach taken, most scholars acknowledge that the concept of religion is a fuzzy and imprecise one.