A popular argument -- sometimes developed with sophistication, other times presented rather barely and vulgarly -- has it that morality requires theism. The claim is not that you must believe in God in order to be good, as if there could not be good atheists. Rather the idea is that the whole concept and enterprise of moral action requires the existence of God in order to make much sense. "If God does not exist, anything is permitted" -- that is the oft-repeated line.
This argument can be developed in such a way as to be a good and powerful one, I think. Some persons, however, have tried to run the reverse argument: the argument that moral practice is actually incompatible with theism, with believing in God as well as in the actual existence of God. It sounds surprising, it may seem strange, but initially the argument has an air of plausibility. How does the argument go?
Consider the case of some grave moral evil: torture, or kidnapping, or starvation and famine, or whatever. The idea is that if God exists, he would not permit such a thing to exist unless he had a sufficiently good reason. Supposing then that he does exist, consequently the occurrence of such an evil and misfortune must have a reason which justifies God. But if God is justified in permitting it to occur, why then should we interfere? Why try to prevent imminent evils, or else to alleviate actual ones, if God has reason to let them occur? It would seem that belief in God requires a hands-off approach to the evils of the world: God's got his reasons for permitting them, therefore don't worry about them. But surely such a thing is monstrous and undoes moral behavior altogether. Therefore, the conclusion is drawn, morality and theism are inconsistent.
Though this argument may seem initially plausible -- and certainly to a fair number of atheists it is really plausible -- it is not actually all that good, at least not in my opinion. There are a few things that could be said in response.
In the first place, this argument as such does not prove that morality is compatible with atheism. The argument here is that in a theistic universe, we would lack adequate moral motivation to seek to prevent or lessen suffering in the world; the fact that God's permitted it is a reason not to interfere, or so they presume. But to suppose therefore that morality is compatible with atheism is a fine non sequitur if ever there were one. The arguments of the theist plausibly show that moral practice does not fare well under atheism, either. There is no judgment, there is no life after death, there is no ultimate reckoning -- all these things compromise the motivation to be moral in a universe where there is no de facto judge beyond whoever's got the strongest arms and guns.
But more to the point, the argument itself is not compelling; it makes some drastic logical leaps which are not strictly speaking valid. That God has reason for permitting X to occur does not entail that I have sufficient reason for not interfering or preventing X. That is an invalid inference insofar as God and I are different agents who are not on a par; he has different goals in mind and a different knowledge of the facts, whereas I have my own unique and limited position from which I must act. God has reason to permit an evil to occur, but I have reason to prevent it and stop it if it has already started.
Beyond that, the theist also believes that God himself demands of her that she work to prevent evil or else help those who are suffering. For instance, Jesus uses the parable of the Good Samaritan -- a case perfectly suited for the philosophical problem we are here considering -- in order to teach a man, "Go and do likewise." Part of becoming a human in the world as God intends us to be is "love thy neighbor as thyself"; this implies that I act to help when she is in danger, as much as I would try to save myself and want others to help, too.