Doomsday cult is an expression used to describe groups who believe in Apocalypticism and Millenarianism, and can refer both to groups that prophesy catastrophe and destruction, and to those that attempt to bring it about. The expression was first used by sociologist John Lofland in his 1966 study of a group of members of the Unification Church of the United States in California, Doomsday Cult: A Study of Conversion, Proselytization, and Maintenance of Faith.