There is No Problem of Evil
There is the oh-so-common atheist argument against the existence of God that is called The Problem of Evil argument. It looks like it started with the old Greek philosopher, Epicurus. In short, the argument says that if God existed He should have made the world a nicer place than it is. Since the world has plenty of terrible problems in it either God does not exist or He is just not a very nice guy.
The argument is nice and fine and logical given a key assumption that goes into it. Unfortunately for atheists that key assumption that starts the argument is just plain wrong. If you start your logic with a false assumption then don't expect the conclusion to be right!
The world was simply not designed to be perfect, it was designed to be educational. God simply has a lot of souls who He knows will take to sin (selfishness) like ducks take to water. He places them all here in specially selected locations in time and space and then lets them go around doing many of the sinful (selfish) things that they want. They get to observe how bad the world is, what with wars, natural disasters, crooked politicians, greedy people, diseases and so on. If they're sharp they will notice the selfishness in other people and then notice that they've got a problem too. They'll get to notice how bad their own choices are. Others notice that this world without God is meaningless and empty.
So once people here on Earth have been educated about evil and what a world without God is like, God basically goes around asking people if they are happy with this world and themselves or would they rather live in a better world. This better world is a world WITH God and it can only be achieved by giving up your sinful (selfish) nature and asking God to make you over into a new and perfect person. Clearly some people do accept the lesson and go on to follow God. They make it to that perfect world. Clearly other people (the Bible seems to say most people) are content with the way they are. So they're happy with being sinful (selfish) people. They go on to Hell, a place that is filled with totally selfish people. In the end, everyone gets exactly what they want, exactly what they believe in. Giving everyone exactly what they want is just totally fair.
Atheists have another gripe as well. Atheists are forever complaining that God in the Bible is, especially in the Old Testament, a pretty nasty guy. Of course the answer, once again, is that what God does is meant to be educational. In Mad Magazine they once quoted Alfred E. Neumann as saying "Learn from the mistakes of others because you'll never live long enough to make them all yourselves." It is remarkably good advice. And this is what is going on in the Bible. Far from being nasty, God is trying to educate us. He's trying to keep us from making the same mistakes other people have made. That's loving. So the interpretation that God is a bad guy also comes from the incorrect assumption that goes into The Problem of Evil argument.
So again, the flaw in The Problem of Evil argument comes from the fact that FIRST, God must educate us about good and evil, which is to say unselfish and selfish. Once you are educated you are free to choose the life you want for all eternity. Totally fair. Perfectly reasonable.
Actually, there is a Problem of Evil: it's why so many people want to be sinful (evil) rather than good and why do so many people not want there to be a God? Atheists, answer that one!