I agree that we currently have no objective proof in the matter, either for or against. I don't think, however, that we must be omniscient in order for this proof to exist. If God came down in a cloud of thunder and made it very clear that he was God, I would consider that solid proof of God's existence, even though I still might not know the number of sand grains in the world.
I have thought about this a lot, as I had a "God" experience when I was a child. And at the time, I was thoroughly convinced that what I was experiencing was "God". Yet as an adult, I still have to wonder. Could I have somehow hypnotized myself? Could I have has some sort of brain aberration? And if this "God were standing before you and I, how could we be sure that it wasn't some sort of space alien with advanced technology, or a really good magician's trick?
In the end, I can think of no way that "God" could prove to me that he's God. I can always find a reason to be skeptical.
Religion "works" for many people. Belief in God "works" for many people. I do not contest these facts, and I do think they attest to the fact that religion can be, in fact, a good thing for humans. But those statements are saying something different than "God works for people." God could be the reason religion works for people, but the simple fact that it does work, does not point exclusively to God's existence.
"God" is an idea. The question at hand is, does the idea we hold of God in our minds have any corresponding existence in actuality. Our experience and knowledge of actuality is very limited, and so we can't really know the answer to that question, I don't believe. But we can test the idea against actuality as we experience it, to see if the idea at least holds water in that small arena of reality that we can know and experience. And this is exactly what that religious prescription I posted, does. And that's why when we discover that it does work, we can use this discovery as evidence in support of the reality of the idea of God that we hold.
I feel it's similar to the theory of evolution. We invented this theory, but we didn't know if it corresponded to actuality or not. So we tested it against whatever small aspects of actuality we could, and we have discovered that the theory "works" (in that actuality responds consistently and predictably according to the theory).
There are still more questions about these theories to be answered, and more "tests" to be done. But so far, the theory of 'God" works for most people, which is why most people hold on to it. And it works beyond that of mere chance, suggestion, and superstition.
Religion is a powerful motivator. Strongly held beliefs tend to be equally as strongly acted upon.
Around Christmas time, kids tend to be on their best behavior. Why? Because Santa might not bring them that particular present if they aren't good. Their (erroneous) belief in Santa Claus causes a very real change in behavior.
But "Santa" is a symbolic conceptualization, over-simplified for children. We give gifts to those we love. We love those (children) who behave the way we want them to behave. So if children want gifts, they must please us with their behavior. This is the idea embodied in the whole Santa-concept.
There are several ways in which the Santa concept differs from a God concept. One is that it is disprovable. Second is that it's over-simplistic, and third is that it's based on humans manipulating other humans. I will admit that such over-simplistic and manipulative god concepts exists, and unfortunately they do work (manipulate) the weaker-minded among us. These are examples of people using lies and fear and rewards to control and manipulate other people. I don't believe this is legitimate religion. As it 's an abuse of theology.
Heaven's Gate cult members all committed suicide in a belief that the Earth was soon to be destroyed and leaving it through death was the only way to assure survival in the next "level". Here is another erroneous belief shown to effect behavior.
Well, we don't actually know that it's erroneous, do we? Maybe Jesus really was waiting for them on that space ship hiding behind the Hale-Bop Comet. This is an example of religious extremism, or perhaps group psychosis. I don't know what to say about it except that it is extreme, and rare. It is not the norm, and therefor does not inform us about the norm, I don't believe.
In the Bob example, you claim that if you can show it is possible for Bob to have killed his wife, then that possibility is evidence that Bob killed his wife, even if Bob did not in fact kill his wife. It's that last bit that gets me: can you call something evidence if it does not in fact support actuality?
Certainly. "Evidence" is really just a collection of facts that support a hypothesis. It is not proof, and therefor the hypothesis could still be wrong. But in most cases evidence is all we're ever going to get. We can't have proof. And because evidence is all we have to work with, we have to take it seriously, but with skepticism, too.
Bob may not have killed his wife, but it's important that we know that he could have.