I read an interesting article by WL Craig regarding the necessity of God's existence. Interesting, that is, because it makes what seems to be an obvious leap of logic to conclude that God exists necessarily. Here is what he said:
So is it logically possible that God not exist? Not in the sense of metaphysical possibility! There is no strict logical contradiction in the statement "God does not exist," just as there is not a strict logical contradiction in saying "Jones is a married bachelor," but both are unactualizable states of affairs. Thus, it is metaphysically necessary that God exists.Let's break this down, shall we?
We have here the germ of the ontological argument for God's existence. For if it is possible that God exists, there is a possible world in which God has necessary existence. But then He exists in every world, including this one. Thus, the atheist is thrust into the awkward position of having to say that God's existence is impossible. It is not enough to say that in fact God does not exist; the atheist must hold that it is impossible that God exists—a much more radical claim!