Religion is an abstract concept that has been used to taxonomically sort a vast variety of human social practices. As the semantic range of the term has grown and shifted, there have been two kinds of philosophical issues that have arisen over how to understand this taxon – issues that are likely to be similar to those that are raised for other abstract concepts that are used to categorize cultural types (e.g., “literature” or “democracy”).
The first concerns how much of a necessary and sufficient condition it is for something to be called a religion. There are those who think that one must have both a substantive and functional definition, but that the substantive definition must take priority. A common example is the view that to be religious a person must believe in a disembodied spirit or cosmological order and that this belief is based on an empirical-nonempirical distinction. This approach, which is sometimes referred to as Verstehen (German for “understand”), has been criticized by those who point out that many social phenomena are not clearly sacred or profane and that there is no empirically-non-religious distinction that can be universally applied.
Other scholars have favored what might be called polythetic or family resemblance definitions. They argue that the various things called religions have little in common besides some degree of analogical similarity and that the term can only be understood as a classificatory concept. To this end, they have argued that when enough of the characteristic features of a religion are present in a given culture to a sufficient degree, then that practice or belief should be labeled as a religion.