In Vietnam, perfectly normal men who should have led perfectly normal lives were killing others and destroying homes. They were in self-defense mode. They felt threatened and it justified their actions to them. Man is inherently good. Man has a natural instinct to help and do the right thing.
Evil is seeded and grown when combined with a survival instinct.
Evil replaces fear. I know it's a dream. Hopes and dreams are the only things that get me up in the morning, these days. I remember that stuff. Race, religion, politics, there's always something to stand in the way of the Golden Rule.