As we accumulate more and more knowledge, plausible scientific theories become more and more probable.

This is an interesting post, since it seems to contradict itself.
While I agree that we can put measurable probabilities on hypotheses, I'm less certain how to do that on complex theories like evolution (not the rather simple darwinian one, but the modern theory), so I tend to think of such claims as "just so stories". (Of course we can use bayesian methods to find the best theory in simple cases, like cladistics or cosmology, they seem to be excellent for that!)
Now, if we can use conditional probabilities, we should be able to say that natural theories explaining observed data increases the conditional probability that the universe is completely natural. That would be a "religious proof" of atheism, ultimately based entirely on data.
I wouldn't be happier than if this would be an acceptable procedure. But perhaps this instead points to the problem of making a single demarcation criteria tells us what is a good theory, including criteria based on bayesian statistics.