All good people are appalled by the sufferings of the innocent. When an innocent person is struck by a painful disease or tortured or murdered, we naturally feel sadness and helplessness and rage. Many people have claimed that such suffering is proof that God does not exist. The argument goes like this: God is all good and all powerful. Such a God would not permit unnecessary suffering. Yet we constantly observe unjust suffering. Therefore, at least one of the premises about God must be false. Either God is not all good or God is not all-powerful or he doesn't exist.
What's wrong with this argument?
First, let's examine what we mean when we say that God would not permit unjust suffering. There are two categories of suffering: suffering caused by human beings, which we call moral evil; and suffering caused by nature, such as earthquakes and cancer.
Free will explains how God would be good and allow moral evil. Because God has given people free will, they are free to behave against God's will. The fact that they do evil is not proof that God is not good. In addition, if there were no God there would be no absolute standard of good. Every judgment presupposes a standard, and that's true of our moral standards, too.
What is our standard for judging evil to be evil? The most we can say about evil if there were no God is that we, in our subjective taste, didn't like it when people did certain things to other people. We wouldn't have a basis for saying an act was bad - only that we didn't like it.
So the problem of human evil exists only if God exists.
As for natural suffering, that poses what appears to be a more difficult question. We see an innocent child suffering - say from an incurable disease - and we complain. Understandable. We don't like it. It shouldn't happen. Understandable. But it's illogical to feel that unless you believe in God.
So, if you do not believe in God your subjective feelings are the only basis upon which you can object to natural suffering. How is it your not liking something is evidence for God not existing? Think about it. It's just the opposite. Our judgments about natural and human evil presuppose the existence of God, which is the standard. If there is no God there is no good or evil. It's just nature doing what it does. If nature is all there is there is absolutely no need to explain why one person suffers and another doesn't. Unjust suffering is a problem because we have a sense of what is just and unjust. But where does that sense come from? Certainly not nature because there is nothing 'just' about nature. Nature is only about survival.
What, in other words, does it mean for suffering to be unnecessary or wrong? How is that determined? Against what standard? Your private standard means nothing; my private standard means nothing. We can talk meaningfully about suffering being unnecessary or wrong only if we have an underlying belief that a standard of right and wrong exists. If that standard really exists it means there is a God.
Moreover, the believer in God has an incomparably easier time - both psychologically and logically - than the atheist in dealing with the problem of natural suffering. If you accept that a good God exists, it is possible to also believe that this God somehow sets things right; if not in this world then the next.
For the atheist, on the other hand, no suffering is ever set right. There is no ultimate justice. The bad win and the good suffer. Earthquakes and cancer kill. End of story. Literally.
If nature is all there is, how can a sensitive person remain sane in a world in which tsunamis wipe out whole towns, evil men torture and murder innocent victims, and disease attacks people indiscriminately? The answer is - it's not possible.
Is that how you want to live?