Religion is a genus of social formations that is most paradigmatically represented by the so-called world religions (Judaism, Christianity, Islam, Hinduism, Buddhism, Confucianism, and Daoism). The term also applies to beliefs and practices that have not been given a name but are found in one culture or another. The concept of religion is a taxon that encompasses many different kinds of phenomena and that is not easy to define. It is often contested whether certain types of activities should be included in this genus or not.
The question of how to define religion has been a major problem in the study of religion. It is tempting to try and come up with a general definition that can be applied across cultures, but this is often not possible. Such a univocal definition would quickly prove to be inadequate and could lead to a sort of lowest common denominator that serves no purpose for comparative studies of religion.
A different approach is to develop a functional definition that defines religion as those beliefs and practices that serve some purpose. Such an approach can be problematic, however, in that it may tend to exclude other types of activities that have important functions in particular cultural settings. This is sometimes referred to as a functionalist bias. In addition, a substantial definition that focuses on belief, personal experience, and the dichotomy between the natural and supernatural can be ethnocentric and fail to include faith traditions that emphasize immanence or oneness, such as some forms of Buddhism and Jainism.