A few days ago I discovered dualism and gnosticism, specifically the Cathar heresy. It sounded pretty great.
Then I went for a lovely road trip and remembered... I literally worship the natural world. Cathars would call me a Satanist, just like anyone who follows the Old Testament God. Different aspects of the world, but both are Satan's domain under that doctrine. So, my excitement wasn't really warranted.
(To be fair, nature is fucking terrifying. A massive thunderstorm swept through on my trip. I stood under an awning with my boss and a coworker and we just watched it for a whole hour, sharing tales of destructive floods. Years ago I became an animist while cowering in a forest when a thunderstorm caught me bicycling.)
Dualism is still interesting to me though. I think most modern Christians are mostly there, in that they follow Jesus and essentially reject Old Testament teachings. That's fair to say, right? It's different from calling the OT God a different entity (especially Satan) but... how different?
Jesus said "turn the other cheek". The God of the Old Testament demanded "an eye for an eye", and a long list of harsh punishments for minor crimes. How does one reconcile these two testaments? One must be false, and thankfully most Christians choose to reject the troublesome parts of the Old Testament.
But they still officially believe in the whole Bible, and thus grant credibility to the... hrm... the people who follow Old Testament scripture instead of Jesus. The people Cathars would call Satanists, who preach Biblically-mandated hatred and intolerance. Who use the Bible to justify slavery and holy war - because the Old Testament *DOES* support those things in the strongest language.
The New Testament isn't perfect either, but given just a little room for interpretation... The New Testament is good and the Old Testament is, mostly, bad.