That's a good overview but still doesn't solve the problem of evil.
When I was searching during my own dark time of testing I came across a well-written article by a young woman who had been a Christian and was in service to Him somewhere. She was raped and after that said that she didn't feel like she fit in the world of believers anymore and walked away from her faith. Where IS God when injustice happens? Where IS He when we cry out to Him and He remains silent? I know my questions aren't new but they do trouble the mind.
I think we tuck away these doubts and hope we never have to actually LOOK at them but then something happens and there they are right in your face - and God does nothing. Like what happened to that young woman. Where WAS God? Why didn't He help her? I know that theologians have wrestled with the problem of evil and it doesn't look like any have really done a good job of explaining it - unless someone knows some works that have eased the minds of those who question.
Its an ancient question and many philosophers have tried to answer. The two extremes being the Calvinist version of God is to blame for everything, while somehow God isnt the one responsible for the sin, He just predestines it, go figure. The other extreme is that God is really dumb, and just doesnt know what people are going to do so He is trying His best to figure out whats going on and call people to repentance, this is the open theist view.
The middle view is that God knows the future, but has given man free will to do as they please. And judgment is reserved for the last day. I believe this one is the most reasonable one, while not flawless.
The real answer is that we do know in the end justice will be served, and remember, letting people continue on in their evil is not like God is giving it a pass, its the opposite, the longer they continue and the more deprived the come, the MORE HELL there is to pay on the day of Judgment. We know there are degrees of punishment in hell, the Bible does teach it, im sure everyone agrees. So letting someone continue on in their depravity will actually bring them more of a punishment.
Also remember that its not unheard of for God to use evil kings and rulers to do what He wants to accomplish, Jesus' crucifixion is one example of this(Acts 3:28) , Isaiah 10 is another example of this. All the common calvinist proof texts, where I believe they make an error however is, they read these individual cases and read into it that God causes ALL of these things, even though SCriptures only mention some. The Bible also mentions: Hosea 8:4
They set up kings without my consent; they choose princes without my approval. With their silver and gold they make idols for themselves to their own destruction.
So that is my opinion of it, both extremes are wrong and the middle road is the correct view.
TL;DR version: God allowing evil people to live longer and continue in their depravity is not necessarily letting them off the hook, its quite the opposite, they are only adding on to the damnation they will receive on the day of Judgment, since we know there are degrees of punishment in hellfire. Humans have free will to disobey God and sometimes God intervenes, sometimes God does not, these are not for us to make judgment calls on: "
"The secret things belong to the LORD our God, but the things revealed belong to us and to our sons forever, that we may observe all the words of this law." Deut 29:29