The Friendly Atheist provides an apologetics link that would be funny if it wasn't so pathetic. Let's see if I can use all the arguments to "prove" the existence of Cthulhu.
The Argument from Change
We can see that things change. And in order to change, they must have some outside force act on them. A seed cannot grow into a plant without soil, water, and sun acting on it. A planet cannot move without the gravitational force of other objects affecting it. And each item that changes things is itself acted on, ad infinitum.
Since the universe is full of constant change, and is itself changing, it must therefore have something external acting on it. This being, outside space and time, is Cthulhu, who lies dreaming in the inky void.