Lots of really good insight! I really like that you took the time to explain your journey and the shifts in your beliefs over time. I find your perspective very well-balanced.
The way I see it is "darkness" is a non-intelligent force, the counter-force of "light." It will always "lose" to light because it is not actual, it is merely an absence. "Evil" is created by humans who choose to side with darkness. The only reason evil has any power is because humans give it power with their consciousness. However, as evil is built on darkness, it is still at a disadvantage in the face of light.
I find evil to be easy to define. Forcing others works for me. Yet I am a voluntaryist. :)