Gnostic

The word gnosticism comes from the Greek word for knowledge, gnosis (γνώσις), referring to the idea that there is special esoteric knowledge, a key to transcendent understanding, that only a few may possess.

Someone who claimed to have special knowledge, particularly of a religious nature, such as passwords for getting into the heavens or for controlling angels. Gnostic

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also see: Agnostic, Gnosis