Many scholars of religion have tended to use the term “religion” in an analogic fashion, treating it as a taxon for a group of social formations that vary significantly from one another. Among those that have used the concept in this way, most prominent are those who have developed the discipline of comparative religion and studied different belief systems in their historical and cultural contexts. This approach aims to avoid the error of evaluating religious phenomena normatively (a task which is legitimate and unavoidable for philosophy and theology) and instead study them phenomenologically.
Some have gone so far as to reject “thing-hood” and argue that religion is a way of coping with the meaninglessness of human existence, ie it fosters positive illusions that make life worth living. This is the view taken by people such as Karl Marx, who characterized religion as the “opium of the masses” and that it provides consolation for those who live in an oppressive world.
Earlier attempts to define religion have been based on notions that are not necessarily universal to all cultures, as is the case with beliefs in disembodied spirits and cosmological orders. Some have been based on single-criterion monothetic definitions, such as the suggestion of Edward Tylor that religion consists of a belief in spiritual beings, Emile Durkheim’s idea that religion is whatever system of practices unites a group of people into a moral community and Paul Tillich’s argument that religion is that ultimate concern which serves to organize our values.