Gnostics (no matter what their stripe, or how Christian they seemed at first glance, and the philosophy predates the Christian faith) believed:
The God of the world was more or less evil because he made things out of matter.
The True God is only spirit, and each level of being, is less spiritual and more contaminated by matter.
That you have to have the secret gnosis to get out of the matter realm and into the spirit realm.
The Christian sounding gnostics didn't believe that Jesus came here in a real body, because that would mean he was contaminated with Matter.
It gets weird and interesting, and farther and farther away from what most people think of as Christianity the more you get into it.
So why should we really care. There are a lot of gnostic texts out there, easy to get hold of. They have no more validity as scripture to Christians than the Golden Ass does, except that they use a framework of Christian names to spout off what has a lot in common with the Golden Ass and other mystery religions like the Orphic traditions.
Gnosticism sounds similar to Christian Science belief.
Sounds like Scientology, doesn't it? New Age = Old Lies.