Cults are social groups which have unusual, and often extreme, religious, spiritual, or philosophical beliefs and rituals. Extreme devotion to a particular person, object, or goal is another characteristic often ascribed to cults. The term has different, divergent and often pejorative, definitions both in popular culture and academia and has been an ongoing source of contention among scholars across several fields of study.
Beginning in the 1930s, new religious movements became an object of sociological study within the context of the study of religious behavior. Since the 1940s, the Christian countercult movement has opposed some sects and new religious movements, labeling them cults because of their unorthodox beliefs. Since the 1970s, the secular anti-cult movement has opposed certain groups, which they call cults, accusing them of practicing brainwashing.