To learn more about existing human religions, please visit Wikipedia:Religions.
Note: In some novels the subject of human religion is considered, though they are by nature not canon. One TNG novel, Guises of the Mind, has as one of its chief characters a telepathic Christian nun, as well as a visit to a monotheistic member-world of the Federation. Jews, Hindus, Buddhists, and Christians are named as crewmen on the ship, and Data himself considers the study of religion. Characters such as La Forge and Picard seem to accept the existence of some kind of higher Power but do not go further.
Gene Roddenberry himself is said to have rejected the idea of religion lasting into humanity's future, but the series has never officially stated that religion is totally dead among humanity, and Kirk seems to declare himself a monotheist by saying "Mankind has no need for gods. We find the One quite adequate." (TOS: Who Mourns for Adonais?) It is also likely that some humans at least will consider it based on encounters with Bajorans and other religious races.
