sect

Small ideological group, usually religious in nature, that may have moved away from a main group, often claiming a monopoly of access to truth or salvation. Sects are usually highly exclusive. They demand strict conformity, total commitment to their code of behaviour, and complete personal involvement, sometimes to the point of rejecting mainstream society altogether in terms of attachments, names, possessions, and family.

Most sects are short-lived, either because their appeal dies out and their members return to mainstream society, or because their appeal spreads and they become part of mainstream society (for example, Christianity began as a small sect in Roman-ruled Palestine).