The source of evil lies in the suspension of rational thought.
Thanks for the cliche’ but the Bible writer James under the direction of God’s spirit explained why humans engaged in evil, as did many of the other writers, like Paul in explaining how all humans were sinful and why. And King David. And Moses. And Joshua.
I don’t recall any of them bringing up suspension of rational thought, quite the opposite in fact. But maybe you have something else in mind.