I can't think of any scientific test that could be done.
Why not?
You sound like Dawkins; he wants to believe the same thing. But he ends up assuming specific, naive conceptions of god and showing that these gods do not exist. I agree--I don't believe in those gods, either. I don't think there is any way of scientifically testing for God, in general.
So the only god that can exist is one that is indistinguishable from a god that doesn't exist?
Here you seem to be taking a couple of metaphysical positions:
1) the physical world is all that exists
2) there is no knowledge outside of science
This position is "scientism" or "metaphysical/philosophical/ontological naturalism." It goes far beyond the "methodological naturalism" that we use in science. (And as you should know, it is "methodological naturalism," not I, which explicitly makes God scientifically unfalsifiable.)
My point is that without some sort of risky prediction of what we should and should not see in reality then how can one arrive at a belief except through blind faith?
I will freely admit that there may be more to reality than what we have discovered. That is the hope of every scientist, atheist and theist alike. What I want to know is how one goes from saying "there could be something else" to "there is something else"? How does one go from "there could be a god" to "there is a god" without reference to anything resembling reason and logic?