Life, the Universe and that sort of stuff

I was listening in on a conversation between my wife and my brother-in-law about the existence of God the other day. I can't remember how the debate started but it finished with him professing open mindedness on the subject. There might be Something, he thought. Who was he to say?

He tends toward the atheist and the sceptic generally but he didn't want to be dogmatic about it, and neither do I. I feel no need to gratuitously trash other people's belief systems. Belief in some sort of Almighty has a venerable history and here in the UK at least it seems harmless enough and if it means that ordinary people are more likely to get organised and do Good than they might otherwise I'm all for it. And I love old churches, choral music and renaissance paintings.
There is something odd about the whole Existence of God debate though. It's strange to me that there even is a debate. My Bro-in-Law's point as I understand it was that there are so many holes in the science (origins of the universe, evolution, consciousness) - so much we don't know, that, well, why not? Maybe there is a God. Who knows?
It sounds generous and broad-minded. And he's right - Science doesn't know Everything - not by a long way, and probably never will. Anybody who keeps up with the Popular Science media will know that there's a big question about all the matter that is supposed to have formed in The Big Bang. The sums just don't add up, apparently. They call the missing stuff Dark Matter but they know that doesn't explain anything. And then there's all the Anti-Matter. Supposedly there should have been equal quantities of Matter and Anti-matter in The Beginning, but nobody knows where the Anti-Matter's gone.
And anyway, how did the universe big-bang itself out of nothingness to begin with?
Maybe there's a God.

I've been watching the Faithful and The Atheists butt heads on this since I was a teenager, and I've joined in as a sort of Agnostico-atheist. (ie. It's impossible to prove that God doesn't exist, but it seems unlikely and way too convenient.) I personally have a background in ecology so I tend to get embroiled in the Evolution debate rather than the Physics, and I've had some memorable arguments with Evolution Deniers, trying laboriously to explain to them how an eye could possibly happen without being Designed by some sort of Intelligence. I found myself having to go back and back, trying to explain about the function of the lense and then the chemistry of the retina and then nerve function half remembered from my first year Biology. I'd have had to go on to explain about Evo-Devo and Precambrian ecology, in none of which am I an expert. Half the problem was that they just didn't have enough Biology to be able to imagine how it might happen (and yet they expected their opinions to be taken seriously). I don't know the details but I can sort of imagine. The evolution of an eyeball is just not that outlandish to me.
But in any case there was a better argument that only occurred to me later. (Don't they always?)

What I should have said was 'Ok, so you can't imagine how an eyeball could possibly evolve by natural selection. What is your alternative hypothesis?'
They'd look at me like I was an idiot and go 'The Intelligent Designer/Creator is the alternative hypothesis. Have you not been listening?'
And I'd go 'But what do you know about this Intelligent Designer/Creator? Where is it? How does it work? What's it made of? What does it want? How big is it?' And I'd guess they'd say... Well I don't know what they'd say. If they were coming from a religious point of view I guess they might say something mystical about 'The Unknowable'. If they were trying to be more scientific about it they might reiterate the point about the gaps in our scientific knowledge of the universe, which I concede are huge, but that doesn't mean we know nothing.

Going back to the Big Bang conundrum, there are huge gaps in our knowledge but we do know things. We know a fair bit about energy and matter and gravity and how they work. We know a bit about stars and subatomic particles. We have the Hubble Space Telescope and the LHC. We can do the maths and we can form hypotheses and we can test them. To be sure, it's quite a leap to take the physics of objects here on earth and to apply it to objects that existed billions of years ago at the dawn of time. The point though is, even if we had almost no evidence and practically no theories to go on, our knowledge would still be infinitely greater than our knowledge of The Creator, because on that, we have absolutely nothing.
So this is my question. Why is it that Atheists even enter into a conversation with Theists as if there is something to be discussed, as if they are in some sort of equivalent position? The very attempt at an Atheist response gives Theism a status that it does not have.
In fact even if we knew absolutely nothing of the science of the Origins of the Universe that would still not justify the assumption that some Unknown Being was involved.
Our relative ignorance of the science is not comparable to our absolute ignorance of the Creator. They are not comparable hypotheses. There's simply nothing to discuss.

Most Theists of course are coming at the question from a position of Faith.
Simply believing in something even though you have absolutely nothing that could count as evidence in a rational scientific debate is a venerable position and I have nothing to say about that (or not here anyway).
Most people of faith however are not so rigorous. Most do, sooner or later want to claim that they also have some kind of material evidence of His existence. (They may also claim that the Scientists have their own faith - in reason, materialism or some such - something I could refute, but not right now. Another time perhaps.)
Usually though their argument boils down to something like 'Well how else do you explain it?'

This is the problem with My Bro-in-Law's Open-Mindedness, because you could explain it any way you like. You could advocate any of the myriad creation myths that exist and have existed around the world throughout history. You could claim that the stars were sprinkled from the Breasts of the Sky Goddess. You could claim that the universe hatched from an egg. You could say that the universe was sneezed from the nose of the Great Green Arkleseisure. They're all at least as plausible as the idea that there is some unknown being out there, that, for unknown reasons and by unknown means, brought the universe into being out of nothing. Calling It God or The Intelligent Designer simply gives our ignorance a name. It does not even begin to explain anything.