Why isn’t God guilty of “sinning by omission” when He doesn’t prevent something bad from happening?
Why isn’t God guilty of sinning by omission when He does not prevent something bad from happening? God is only guilty of sinning by omission if He has a moral obligation to do something that He didn't do. If we are faced with a circumstance where we might act to prevent something bad, but we choose not to, arguably we could be guilty of sinning by omission. We should have done that thing, but we didn't do that thing, and so we're guilty.
The question is: Does that moral obligation apply to God too? Is God morally obliged to stop any evil that He is able to stop? Well if that were the case, since He is able to stop every evil, then there would be no evil, and there would be no problem of evil. It would also mean in that there would be no creatures that are capable of doing evil. You see, only in a world where you have creatures that don't have moral freedom do you have a world in which there is no possibility of doing evil. God could have created a world like that, there's no question. He did not.
Probably the best answer, generally speaking, for why He did not, is that He had a morally sufficient reason for it. That is, He had a good reason, and when I say good, I mean morally good. There is a better, morally speaking, end that will obtain or be accomplished because God allowed evil for a season. Of course, we see this in our lives. It’s inherent to the whole problem of evil.
We also see this in small ways in our own lives where we realized that the difficult, hard, bad things that we went through – even things that are morally bad, not just bad in the sense of being uncomfortable – are things that, as we walked with Christ and trusted in Him, turned out to have a payoff. Many of us will look back on the old state of affairs, the old circumstances, and say, “It was worth it. I’m better off now. We’re better off now. The circumstances are better off now. Everything's better in ways that really matter. The bad thing turned out for something good.
Simply put, we have moral obligations that God doesn't have. God has a perspective that we don't have. He is not obliged, in my view at least, to get rid of every single shred of evil. Sometimes, getting rid of every shred of evil is going to have ramifications to lessen the abundance of good that will come from the world the way God has allowed it to be.
Who knows whether the balance is going to be on the good side or the bad side? In other words, we’re taking a chance, aren’t we? How do we know it's going to be better for allowing this evil? I’ll tell you who knows. Not me, not you, but God. That's where we're going to have to leave this one. God has the insight. God has the perspective. God has the knowledge to know whether or not the moves He made and the evil He allowed will be morally justified in the long run or not. We have no way of answering that particular question.