The world is full of war, starvation, racial prejudice, death, political dishonesty, etc, etc. How could a good god have created a world that is in such a mess? Doesn't this indicate that there is no god?
This is perhaps the strongest argument against the existence of a god. On the surface, it is hard to think otherwise. But here are five questions that may help us think through this issue.
It is hard to escape the feeling that something is wrong with the world, and to blame God or disbelieve in a god because of that. But the above questions take a lot of of the sting out of the argument - it is hard to maintain the rage against God without a strong basis for our views about right and wrong, and in a world where we clearly gain such pleasure and joy.
But, on its own, it still seems that suffering and evil make it harder to believe in a good God. Our final choice will probably depend on how strong we think the evidence for God is. If we think that God is the only, or most likely, explanation for the creation of the universe or its amazing design, or if the strength of the historical evidence for Jesus lead us to conclude that God indeed exists, then we can only admit that we cannot understand the extent of suffering and evil but we still trust God. But if we find those arguments unconvincing, suffering and evil will likely cause us to disbelieve.
Comment on this topic in the discussion section
This has been a very brief treatment of a very difficult subject. Consider it in a little more depth at God and Evil.