(Gr., gnosis, "secret knowledge.") Religious movement of the second century C.E. emphasizing the redemptive power of esoteric knowledge, which is said to be acquired neither by learning nor experience but by direct revelation from God. The Christian church—its doctrine, symbols, canon, structure, and authority—developed largely in reaction to Gnosticism. See Hans Jonas, The Gnostic Religion: The Message of the Alien God and the Beginnings of Christianity.