The term religion has evolved from its Latin origin, religio, to mean “scrupulousness” or “devotedness.” Today, it is a social category that includes a broad range of beliefs and practices. Scholars have attempted to classify the different religious systems, and one way is by what or who they worship (if anything). Religion also includes sacred rites or ceremonies, holy books, a clergy, and sacred places and symbols. In addition, most religions believe that salvation is possible—either in a literal sense with life after death or in a more symbolic sense with the attainment of an end to suffering such as nirvana.
The need for religion arose, according to one theory, from human curiosity about the big questions of life and death and from fear of uncontrollable forces in the natural environment. The need to control the uncontrollable led humans to attempt to manipulate the environment through magic and, later, to supplicate to gods or spirits for help. This supplication grew into the religions that are recognized now around the world.
Religions differ in their beliefs and rituals, but most of them have similar elements. They all have something to do with morality—how people should live their lives. They all believe that their gods have some kind of power to reward or punish them, and they all try to communicate with these gods through prayers or offerings. Most religions include a concept of life after death and, in many of them, the dead are resurrected.
Some scholars, like the German philosopher and revolutionary socialist Karl Marx (1818-1883), have studied the role of religion in societies, believing that it is a way for the poor to vent their anger and frustration at a system that treats them unfairly. Others, such as psychologists and neuroscientists, have examined the relationship between the brain and religion, and they have suggested that there are certain psychological needs that can only be fulfilled by religion.
The concept of religion has expanded and shifted over the years, but scholars still struggle to categorize the different faiths. The different ways in which scholars have defined the concept are not necessarily mutually exclusive; however, some approaches are better than others at capturing the essence of religion. For example, Emile Durkheim (1912) and Paul Tillich (1957) have taken a functional approach to the idea of religion, defining it as whatever practices unite a group into a moral community—whether or not those practices involve belief in unusual realities. Other scholars have argued that the concept of religion should be based on function rather than substance, and that there is no such thing as a necessary and sufficient definition of the term.