In the past few days and weeks, however, I have been thinking along rather different lines: not about the existence of God as such, but of the nature of God in terms of the properties that worshippers appear to believe He must have to qualify as a deity, rather than just a bloke who is just bigger or cleverer than anyone else. In other words, there must be clear qualitative differences between Man and God and, as far as I can see, they boil down to two things - immortality and omniscience.
I looked at immortality in a recent post, in which I used somewhat literary arguments to propose a necessary trade-off between immortality and sentience. In other words, you can be immortal, or you can be sentient, but you can't be both. Of course, this view would be threatened by the discovery of immortal, sentient aliens, but here my criterion of qualitative difference comes into play. There is a clear distinction between a being that is immortal, and one that simply lives an awfully long time.
To be immortal, one must be in existence for eternity, presumably outlasting the Universe. This must mean that a deity that is immortal exists outside the Universe, and therefore outside the space-time continuum, in which case the question of birth and death has no meaning. Beings that live outside the Universe are immortal by definition. One-Nil to God.
Not so fast - I don't know about you, but I'd say that things said to exist outside time do not exist at all, and even if they did (or could) they could have no influence on what happens inside the Universe.
To be sure, one might now launch into arguments about the many-worlds interpretation, or branes or string theory and whatnot, but to do this runs a risk that's central to why Intelligent Design and Dawkinsian Atheism are both failures. For the faithful to seek plausible evidence for the physical evidence of God is at the very least an implication that one's faith is weak, because faith should not require physical evidence. Conversely, to seek to disprove the existence of God by some apparently scientific test or process of falsification, as Dawkins suggests in The God Delusion, is also in error. It is in the nature of faith that one cannot prove the existence or non-existence of God. You can't seek to prove that God exists, because if you did, he wouldn't - he'd just turn out to be a very powerful alien instead. And that's not what we mean by God.
The omniscience question is simpler and, amazingly, hadn't occurred to me until I started to read Impossibility by John Barrow. At first sight, there doesn't seem to be anything implausible about omniscience. However, as Barrow demonstrates using an age-old trick I thought I knew, there are limits to how much one can know, because one can make statements whose truth or falsehood can never be established. Barrow looks at the paradoxes inherent in the statement
THIS STATEMENT IS NOT KNOWN TO BE TRUE BY ANYONE
but I prefer it in the classic form of the Epimenides Paradox.
'ALL CRETANS ARE LIARS'
said Epimenides, who was a Cretan. If the statement is true, then it must be false, because we've been told it by a Cretan. But if it's false, it must be true, again because we've been told by a Cretan. In other words, there are statements about the world whose truth or falsity cannot be determined, therefore it is mpossible to know everything. Omniscience fails - and, importantly, it fails whether one is Man or God, because the paradox is made without reference to the nature of the hearer. It is logically impossible to know everything, so omniscience is ruled out.
Well, you might say, perhaps God knows almost everything - but that demotes him from Godhead to just a bloke who is more informed than you. We might try to sneak round the problem by saying that we cannot know what God knows, which is true, but it's true for any two beings. I don't know what P Z Myers knows, or Richard Dawkins for that matter, and I strongly suspect that neither of these people are deities, though at least one probably thinks he might be. So we're back where we started.
To sum up - One can assert that God is immortal but to do so invokes physical problems which, in the world of faith, we have no business asking. We are on more secure ground by saying that God cannot be omniscient. This conclusion stems from logic, and holds true irrespective of God's location or physical state (which is why the Barrovian argument is so much better than the Dawkinsian). If God is someone who knows nearly everything (and stop me before I invoke Heisenberg) than he's not God. He's more than a Very Naughty Boy, but the point is made.