A Modal Argument from Evil
Some worlds are more evil than ours: we don’t live in the worst of all possible worlds. Some are a lot worse than ours: only the wicked prosper, disease is rampant and deadly, virtue leads to imprisonment, people are executed for singing in public, deep depression is the norm, and so on. One would think that if such a world had been created by an intelligent being, that being would have to be a devil or else completely incompetent at world creation. Clearly this world was not created by an omniscient, omnipotent, all-good God. The properties of the super-evil world and the properties of the traditional God are not compatible. So God does not exist in every possible world. He is not therefore a necessary being. But God is (or would be) a necessary being. Therefore God does not exist. His non-existence in one world entails his non-existence in every world, including ours. You might not think the degree of evil in our world is sufficient to disprove God’s existence, but surely you would agree that there could be a world so evil as to preclude God’s existence in it. But that undermines God altogether, on pain of declaring him a contingent being. For in some worlds atheism is true, and just where God is most needed. Surely an omnipotent God would make sure that such a world does not exist: but it does. And if God does not exist in a world because that world contains a large amount of evil, how do we know that our actual world is not such a world? It certainly contains a good deal of preventable evil. The mere possibility of a world with no God undermines the whole idea of God’s existence.
 In some worlds maybe God does plausibly exist—the heavenly worlds. If a possible world is a paradise, we might suppose that it must be created by a God-like being. But our world is not such a world—or else we would already be in heaven.