Apostasy is the formal disaffiliation from or abandonment or renunciation of a religion by a person. One who commits apostasy (or who apostatises) is known as an apostate. The term apostasy is used by sociologists to mean renunciation and criticism of, or opposition to, a person's former religion. The term is sometimes also used by extension to refer to renunciation of a non-religious belief or cause, such as a political party, brain trust, or, facetiously, a sports team.