sect

noun

• a group of people with somewhat different religious beliefs (typically regarded as heretical) from those of a larger group to which they belong.
• often derogatory a group that has separated from an established Church; a nonconformist Church: two of the older sects—the Congregationalists and the Baptists—were able to increase their membership dramatically
• a philosophical or political group, especially one regarded as extreme or dangerous: the radical sect Friends of the Earth campaigned against aerosols containing CFC gases