Sect

A sect is an noun meaning:

1. a body of persons adhering to a particular religious faith; a religious denomination.
2. a group regarded as heretical or as deviating from a generally accepted religious tradition.
3. (in the sociology of religion) a Christian denomination characterized by insistence on strict qualifications for membership, as distinguished from the more inclusive groups called churches.
4. any group, party, or faction united by a specific doctrine or under a doctrinal leader.