The word religion encompasses a vast range of practices, beliefs, and institutions. Some scholars, especially those inspired by Continental philosophers such as Friedrich Nietzsche and Michel Foucault (see Nietzsche, Friedrich and Foucault, Michel), argue that the varying semantic range of the term reflects the fact that the concept itself is an invented category. Others, especially those influenced by sociological functionalist approaches such as Emile Durkheim (see Durkheim, Emile), argue that any system of beliefs and practices that functions to unify people into one moral community can be considered a religion.
This broad definition of religion is a powerful and useful one in practice because it allows the study of any non-theistic faith that seeks to integrate belief and practice. It also makes it possible to distinguish between different types of secular systems. In addition, the definition focuses on how beliefs and practices manifest themselves. These manifestations can be private or public, disciplinary or not, and personal or collective.
Philosophers have wrestled with how to define religion since the very beginnings of modern philosophy. The resulting array of definitions has been impressive in its breadth and variety. This article presents a brief history of the evolution of the term, and provides a taxonomy of a number of different kinds of definitions (substantive, functional, mixed, family-resemblance), along with some critical commentary.