I'd suspect most Christians have no clue how on planet Earth, early Christians managed to theologically move from the 'gospels' and 'Paul' all the way over to a never-never land of everything being not what it is! And jewish Christians, no less! Within a fairly short time.
https://www.logos.com/product/7145/the-new-testament-and-gnosis-essays-in-honour-of-robert-mcl-wilson
is a very good read. It's about 30 years old, but a good series of different scholars attempting to understand the process/beliefs. Price-wise, it's a bit hefty, but certainly not in the 'academic' price range.
I liked it primarily because of going through the NT 'tightly' and not making assumptions. And not unexpectedly, it achieves no 'answer'.
Recommended.