- Functional definitions - Focus upon the functions that religions perform in society. However, things that are clearly not religion could end up being classified as religion, for example football.
- Substantive definitions - Concerned with the content of religion rather than its function or purpose. However, religions are so different that it is hard to look at the content of them all.
As there are problems with both types of definition and as religion is very difficult to define, it may be better to just pick out their key characteristics.
Glock and Stark identified five key characteristics common to all religions:
Beliefs - a member of a religion will accept the major beliefs of their religion. Practice - a member of a religion will engage in certain practices. Experience - a religious person will have some experience of, or communication with a God. Knowledge - a religious person will have some knowledge and understanding of the teachers of their religion. Behaviour - a religious person will be expected to adopt a behaviour that fits into their religion.