Thats interesting. It seems to indicate that Gnosticism predated Jesus as it was already incorporating selective Jewish literature.
One of the things that I wonder about is that we clearly see a Gnostic schism in the early church because the Apostles spent a great deal of ink battling their error. John and Paul seemed especially specific towards Gnostic error. However no one ever calls them Gnostics. That I find curious. Of course Jesus identified the Nicolaitins in Revelation and it is widely held that this is who Paul was addressing when he said, “Shall we go on sinning that grace may abound? God forbid!”
But Johns Apocalypse came much later I suppose.
The authors assertion that Gnosticism is on the rise in the modern church could have used some specific references. Who does he think are the New Gnostics?