A cult was a cohesive group of people who follow a set of beliefs or practices that are outside the mainstream of a particular society. Bajor featured one such group, the Cult of the Pah-wraiths. They came to prominence in 2374. (DS9 episode: "Tears of the Prophets") The Klingons had the Cult of Kahless to contend with. (TOS novel: One Small Step)