'Gnosticism' is the label which draws together a broad spectrum of strange, quasi-Christian belief systems that arose within and around the early Christian Church and challenged both its orthodoxy and its very existence. The creators of this alternative spirituality were dualists who believed in the absolute distinction of matter and spirit, and taught that the only way in which humanity can be drawn back into the being of the one, true God, is through the revelation of a special saving knowledge: the 'Gnosis'. But their challenge to the Christian faith failed and the gnostics faded away. Or did they? This volume provides a clear, concise, and objective overview of the phenomenon of 'Gnosticism'.