The Gnostics were an interesting group and yes, Nate‘s spot on with that.
Competing Gnostic groups used whatever the latest imagery was to bring into their groups and they treated the up and coming Christianity no differently than they did the other religions of the time period.
Secrecy was a big deal. Everything was in code as it were.
There’s a good reason why the early Churches had the Ecumenical Councils. They approached it with great seriousness – it was high Science of the day – and very important to get it right because, after all, if we’re but a blip on the radar screen of the Universe and everything important happens AFTER we leave here, well, you’d better get it right.
And, the Gnostics were interfering with that for their own purposes.