Scientific models are man made abstractions on a reality that we cannot prove. You obviously put a lot of faith into those man made abstractions.
To say that a theistic god is a man made invention is an assumption on who created it. That would be distinctly eliminating the possibility of alien life forms.
Also you misuse Occam's Razor. It can't disprove anything without empirical data.
The bible is a man-made invention. The stories in it are disseminated by men. That does not disprove that there is a God who can interact with the real world in some way or other. It just means that as scientific knowledge refines their theories so must religion.
Also a few points, I'm an Aerospace Engineer. I know that there are tools that expand what our senses can observe, but they still must display information in a way that we can observe.
I'm curious though, would you mind clarifying this statement. >>It presupposes a lot more to assume an intelligent being capable of creating universes who either spontaneously came into being or always existed than to assume the same thing about the universe itself (i.e. dumb matter).
What about a hypothesis of a deistic God makes it no longer needed? If you move away from the physical sciences into those that study the human psyche, you'll see that much is left unexplained. It could be argued (albeit blindly) that any such hypothesis is no longer needed.
Natural sciences and behavioral sciences have no business explaining away each other. Religion is a behavioral science. You may deem behavioral science as superfluous, but it can't be cut away.
At least not yet.