The duality of good and evil

What was created was good. But God created in us (and, apparently, in the serpent) something that was very dangerous: choice. Did sin enter the world because the serpent chose to influence humanity's choice, or because humanity chose to turn against God? Or does the serpent speak to us only in demonstrating how sneaky our own ego can be?

I think we are basically good (for we are created in the image of God), but we are terminally flawed because the sin of human ego--whether the original sin, passing through the generations, or our own, or something in between--has impaired our connection with God. So one could paraphrase the quantum physics concept of duality: we are both basically good with the ability to do evil AND basically evil with the ability to do good.

It's strange (or maybe not), but with my physics background, I find frequent opportunities to use the language of science--and quantum physics in particular--in discussions of Christian theology.