<p>Gnosticism - derived from the Greek word gnosis, to know - is the name given to various religious schools that proliferated in the first centuries after Christ and, at one time, it almost became the dominant form of Christianity. Yet some Gnostic beliefs derive from the older Mystery traditions of Greece and Rome, and the various Gnostic schools came to be branded as heretical by the emerging Christian church. Indeed, although some Gnostic bel...