Religiousness is a complex phenomenon that cannot be defined in the simple, straightforward way that one might think about a thing like “literature” or “democracy.” That complexity stems from the vast variety of beliefs and practices that can be called religion. Historically, attempts to classify these diverse phenomena have been “monothetic,” operating on the classical view that a given concept will be accurately described by instances sharing a set of defining properties. In recent decades, however, scholars have developed a new approach, called polythetic, that embraces the idea of a family-resemblance concept rather than one of necessary and sufficient properties.
Some critics have objected that substantive definitions of religion resist a certain ideological image of human beings as passive social actors who are manipulated by an external force. In this view, the role of religiousness is to provide a sense of identity and meaning for such passive social actors. Moreover, many of the practices and beliefs classified as religious today are not particularly distinctive. Belief in the afterlife, supernatural beings, or a specific cosmological order are fairly common throughout the world.
A further problem with functionalist approaches is that they tend to exclude faith traditions based on worldview or ethos, such as Buddhism, Jainism, and Daoism, from the category of religion. Such faith traditions, although often not viewed as “religions” by their adherents, nonetheless are powerful forces in the world and have profound influence over people’s lives. This is why it is important to recognize the significance of these nontheistic religions.