How can id, ego, and superego be discredited?

People just think evilness is SAAAATAN and the goodness is GAAAWD but I think it's just HUUUUMAN! We all struggle with things in our mind that say to do bad things and say to do good things. The moderator is basically us (ego). Why is everything bad considered the devil possessing you when it could just be how the brain functions. We have id and superego to balance each other out. Ever heard of Imp of the Perverse? Someone said it's discredited but it makes so much sense. Human nature in itself is GOOD AND EVIL combined.