Old trees, one thing I'm trying to get and I think BP may also be after is not what your or anyone else is really providing. Rather than what you are saying, give us an example of what would have to be proof. Not a standard for the test or anything else. Finish the sentence "If I saw or was given credible evidence that ________ happened, I would begin to believe in a god." As an agnostic this question may not be the best suited for you though, so if an atheist could answer it it would be preferred.
I understand what you want (a concrete example that would work as evidence). However due to my ignorance and my awareness of my ignorance, the closest I can give is an abstract criteria that would confirm or deny if the example would work as evidence.
The first thing that is needed is a list of sufficient conditions for Divinity/Godhood/Deity status. (Merely necessary conditions are insufficient for the test)
Next examine each condition for any traits left on actions done by beings with the sufficient condition. If any of those traits are sufficient conditions of a sufficient condition of the actor being a God then you have found a viable test.
The major problem is I do not know if there exist sufficient conditions of godhood much less traits that are sufficient conditions of an action only being done by beings with a sufficient condition for being a god.
So the answer is:
If I saw or was given credible evidence that an action occurred with a trait that was a sufficient condition for the actor having a sufficient condition for being a god, I would
begin have a rational belief in a god.
A test that would cause me to believe god does not exist would be much more stringent than that.
Note: This is my reason talking. Obviously we are all burdened with irrational beliefs. My reason looks down on those beliefs of mine for good reason and as such they are mostly irrelevant.