RE: @4nd7a

The Gnostic Gospels by Elaine Pagels is probably a good place to start, as it gives a good rundown of general Gnostic concepts and historical context surrounding it. It's available on the Internet Archive too, so it's pretty accessible.

However, and hear me out here 'cuz this is advice I received from many professors, I do actually and genuinely recommend Wikipedia diving if you know little about a subject before you jump straight to books. Get a good general idea, always remaining aware it does not make you a specialist, and then check the sources it offers. Google the authors, look at their body of work. Then, look what the works cited by those works and so on.

Of course, not everyone needs or wants to dedicate months of research into a subject they only have a mild interest in, and that's completely valid. Which is, additionally, why I recommend staring at some Wikipedia'ing. If you like what you see, Pagels' is a good start on actual literature about it. And if you want more... Well, you get the idea.