So moral evil does exist, at least at the macro level. Anyone who would deny the reality of evil at the heart of Nazism, the Salem Witch Trials, the 9/11 attacks or the Killing Fields of Cambodia is naive at best. I don't doubt that the participants, for the most part, thought they were doing the right thing in these incidences. But they were unarguably wrong: what they did was evil.
But what, exactly, is this moral evil that differs from natural evil? Moral evil is, as this glossary defines it, sin. Moral evil is doing what we ought not do; turning away from God and doing our own thing for our own reasons.
As Jonathan Edwards asks, "for what is moral evil, if not the perversion of that which is naturally good?" Indeed. Moral evil is quite simply sin. Which causes quite a conundrum. We can all see the moral evil of Hitler. What we often do not see is the moral evil in our own lives. If we accept that Hitler was morally evil, then we must also accept that we are morally evil.
Hard to accept? Moral evil is sin, and Hitler committed moral evil - ergo sin. But all of us have sinned, and all of us will sin. To the extent that we have sinned, we are in the same boat as everyone's default standard of evil. And notice that God does not differentiate between us and him. How so? We have all earned the exact same wages. God doesn't say the wages of some sin is death, and some sins is a stern talking-to. The wages of all sin - any sin - is death. Eating the wrong fruit was sufficient disobedience to curse the world (hence natural evil) and bring death to a creation that was very good. All of us have done much worse than that in terms of volume if not level of malice. Evil is evil is evil - all sin is evil, and all of us have committed acts of evil. I certainly have.
We like to compare ourselves to others, and thing we're not so bad. In real life, I'm a pretty decent guy. I don't know anyone who thinks I'm an evil person; even people with whom I disagree tend to at least act like I'm likable, if misguided. But the truth is that my nature, before God gave me the gift of redemption, was pure evil. Not the evil of Hitler, but the evil of Ron. Yeah, I'm a nicer guy. I do less malicious and heinous things. But even my relatively small sins (though compared with some people, I am a large sinner) are enough to bring about suffering.
So when we ask why suffering exists, it's because we exist and have the free will to sin - and use that free will to sin. We can't blame natural evil on God; it's here because we choose moral evil. If Hitler was evil, so are we. Maybe not to the same extent, but evil enough to curse the world. We can't blame others without taking responsibility ourselves.
That's not the end of it, of course. Though moral evil is real, and it is widespread, it is not all there is. Goodness exists, and we can be redeemed despite our own evil ways. A God who didn't love us wouldn't have given us free will, or having given us free will would have left us to our sin. Our loving God gave us a way back - through His Son.
Moral evil exists. It is everywhere. But it is ultimately going to end. It may not be much comfort now, for some, when suffering seems unbearable. But as real as evil is, and as real as is the suffering evil causes, goodness will ultimately win out. That is the thought that keeps me going when things seem bad. Hard yes. But it's the truth.