Religion is a broad category of beliefs and practices that have to do with the supernatural (as in a god or gods) and its relation to humanity and the cosmos. It also encompasses a moral code that tells people how they are expected to behave toward themselves, other believers, outsiders, and the world at large. There are currently over 6.2 billion people in the world who identify as religious. Among the major religions, Christianity has the most adherents and Islam is the fastest growing. Religions are typically characterized by a shared canonical vocabulary of venerable traditions, writings, history, and mythology that serves as their scriptural authority. Religious tradition often consists of prayer, ritual, scriptures, and laws that establish relationships between believers, the world, and the supernatural realm.
In the last few centuries, scholars have tried to analyze religion using many different approaches. These have tended to fall into one of two categories: “monothetic” and “functional.” Monothetic approaches take the classical view that a concept is so defined by its properties that every example that accurately shares those properties is a member of the class. The problem with this approach is that it is difficult to see patterns in the data or explanatory theories that have the force of law.
Functionalist approaches, on the other hand, are based on the notion that religions have certain underlying causes. These can be psychological or social. Psychologists, for instance, argue that religions are created to serve specific emotional or psychological needs, such as the fear of death or a need for meaning and purpose in life. Neuroscientists have recently discovered circuitry in the brain that they believe is necessary for religiosity.
A third way of looking at religion is to treat it as a social genus. This means that it is a property of human societies that appears in all cultures to some degree. The advantage of this approach is that it allows for a more precise definition of what counts as religion and makes it possible to see trends and gradations within the data.
For example, it is well known that most countries in the world have a religious component to their culture and that the number of religious believers in each country varies widely. It is also true that there are some groups of people in the world who do not consider themselves religious at all. A study of the phenomenon would show that it is possible to have a religion without the belief in disembodied spirits or cosmological orders, just as it is possible to have a social genus without being all-encompassing. Nevertheless, all of these different types of analysis produce quite distinct definitions of what counts as a religion and they give rise to competing arguments about what the term actually means. As a result, the study of religion remains a controversial field. There is no clear consensus about what it is or what it should mean, but there is a continuing need for its study because of the role it plays in human society.