I mentioned gnosticism before here.

A short overview of gnosticism is the most recent episode of Way of the Fathers podcast. It's from a Christian, and more specifically Catholic perspective. One can even say the Church has the knowledge base about it.

The podcast series is well worth a listen if one is interest in church history, and the history of Christendom, and the West. Even the history of philosophy, imho.

Gnosticism never died, and it is quite rampant now. Just take these self-proclaimed political "leaders" and "experts". Or those that are afraid of death and hope technology can make them live forever. Not just narcissistic and stupid but evil.