Well now you've done it... By asserting that God might actually be natural not supernatural puts God under the same microscope as everything else natural.
True.
So if God is natural then we should be able to observe and test his effects on matter the same way we test dark matter, right?
We should be able to test his effects on grey matter in fact.
Ok, so which effects of God can we observe and predict? prayer? nope, that's been shown not to work. anything else?
Woah. First of all, the fact that most humans believe in to this very day, and that they actually PRAY to something they call God would in fact be a "successful prediction" of the the cosmology model I specified as opposed to some other cosmology theory. For instance, modern cosmology theory makes NO predictions about such human behaviors, nor could it.
We can use our "cosmological perspective of choice" to start making some rational predictions about events HERE on Earth.
We can also create empirical experiments in actual TESTS of concept, but the kinds of tests you mentioned are actually "too sloppy" for my liking. I've outlined at least one experiment that might not require that God always "says yes" to our requests.
My advice is stick with the supernatural definition of God like the rest of the theists do....
Sorry. Once you choose empirical physics over metaphysical mythologies of any kind, it's hard to simply "go back". Once the blinders come off, they tend to stay off.
at least they can claim that the reason God leaves no evidence for himself is because he is supernatural.
Whereas I see evidence of God in everything I see.

I like my beliefs much better thank you.
ur gonna dig yourself into a hole with thinking like "god is part of nature." cuz he clearly has no effect on anything... and everything in the universe behaves as if they wasn't a god.
No, not at all. In fact one of the KEY PREDICTIONS of a LIVING God/Universe would necessarily be related to an ELECTRIC UNIVERSE prediction. By selecting this particular belief (pantheism), I've necessarily chosen a scientific path that would insist that this theory would expect that the universe would either:
A) be electrical in nature, not just magnetic in nature
or
B) the theory itself would be falsified.
Remember, it's an empirical theory.
There are a clearly definable set of COSMOLOGICAL implications of this belief system that can be 'tested' against other cosmological ideas, like "dead inflation sky bunnies" (aka inflation) to see how they stack up. Are you going to pass up the chance to EMPIRICALLY COMPARE cosmological concepts and the implication of those concepts as it relates to spacetime?
For instance, no forms of 'dark matter' are required or necessary for life. Likewise no forms of 'dark energy' need to exist for life and consciousness to form in the cosmos. Ditto with inflation. Not one of the mainstream metaphysical constructs is necessary or required in a pantheistic view of the universe.
Some things that we WOULD EXPECT to observe in spacetime are features that are COMMON TO LIVING ORGANISMS on Earth. We should find patterns of energy releases that are repetitious, some that are not repetitious, and lots of *ELECTRICAL CURRENT*.