How I wish I studied maths...
Oh well, back to the problem of God, take a look at this argument (Russel beleived this, at least for a while).
1. God is that of which none greater can be conceived (definition of God).
2. God exists as an idea in the mind.
3. For any x and for any y, if x is only in the mind and y is in reality, then y is greater than x.
4. If God exists only as an idea in the mind, then we can imagine something greater than God, perhaps something just like Him except that it is thought to exist in reality.
5. We cannot imagine something greater than God.
6. Hence, God exists in reality.
You have lots of friends, don't you?
Just giving my side of the story!
I don't think Russell ever believed in the Ontological Argument.
Yes he did and he wrote about it in his autobiography (it's a good read, try it sometime). He belived it until he was 18 and then he became an atheist, until his fourth year at Cambridge when he came to the conclusion that the ontological argument was indeed sound. But later in life he realised he was mistaken and converted back to atheism.
If God can do things we can't comprehend then why did we "invent him" in order to understand the world (which presumeably we can't understand if god is incomprehendable)?