there are a lot of weird theologies out there, some might have a grain of truth but many are mixed up with a lot of half truths.
while they are interesting I wouldnt rely on Cs Lewis or Jean Calvin or Wayne Grudrem to tell me all about God. I can experience God myself, and I can go straight to scripture. This is what The OT is preserved for us and also the NT. God gave us apostles...and Paul was one of those appointed for the gentiles and his words are noted as scripture today thousands of years later.
I dont really need someone else to tell me,so I find a lot of theology books redundant if you read the bible.