Thank you for inviting me to consider this perspective. I hadn't seen it before (we tend to fixate on the fragments of a thread that directly involve us).
I'd offer up front that I don't know that it matters what how we define god, as long as we understand that we are talking about something that, on some real level, transcends the natural world and senses. Since I assert the existence of God, if you're amenable to it, we'll define God as the designer, programmer, creator and administrator of the objective reality to which you refer. Let me know if that works for you. I'll continue with the assumption that you're good with that.
Before we get round to other questions, does this being exist in objective reality?
Or only as a concept / idea / thing imagined?
If the former, [he] has no description that I'm aware of appropriate to a real being, such that if we found a real suspect we could determine whether it was God or not. All the descriptions are imaginary terms, like omnipotent, omniscient, perfect, infinite, eternal &c &c.
(I wonder for example how God knows there's nothing [he] doesn't know [he] doesn't know?)
This point leads me to the thought that testimony exists which asserts that God has appeared, has said, has done, has a description appropriate to a real being, etc. What should one do with that testimony (because it refutes the conclusion that God doesn't denote any real thing)?
There are so many such stories that I suggest the more likely explanation is that Just So stories with gods and devils and heroes and magic are something humans do, apparently related to our evolved instinct to instantly attach a narrative to an unexplained situation and to test it on the basis of such a narrative, rapidly changing it for another until the unknown is either known or no longer seen as a potential threat.
I appreciate your definition of objective reality, though it seems (seems) to dismiss everything real that can't immediately be known about through the senses, or that hasn't at some point in human history been known about through the senses. How would you respond to that summary?
It gives a testable distinction between things that are objectively real and things that are essentially conceptual / imaginary. It also gives an objective test for truth in many cases. Truth is never absolute, only retrospective, of course. For example, the Higgs particle was theoretical, not real, until 2012, when its reality was affirmed. And thereafter there's always been the Higgs particle ─ unless of course our future discoveries show we've misunderstood something.
I use the Higgs particle as an example of how we know we know things. I think my definitions also addresses the question, what do we know to be real and what don't we know that might be real? Dark matter, for example, is presently the name of a problem, not a thing.
Also, it might be noteworthy that in your definition of objective reality you appeal to a collective experience to validate that reality, rather than strictly your own. "...which we know..."
Indeed. The repeatability of an experiment, for instance, is a vital part both of scientific empiricism and scientific induction. If I tell you there are real fairies living in the park near me, your most civil reply would be, 'Really? Show me.' And if I reply, 'Well, they're invisible ...' you may well feel no less doubtful.
"If we can't find..." Would that collective experience include or exclude the testimony I referenced above?
Think repeatable experiment, or perhaps here, repeatable demonstration. Why are all the photos of Bigfoot not really convincing? (Of course extraordinary claims require extraordinary demonstration, as the saying has it.)
Might it be that, to you, the one bearing that testimony is the person who has been pared out of the collective (presumably), as alluded to in the tail end of your objective reality statement, "...then God is only a concept or thing imagined in an individual brain"?
Off the top of my head, the closest I've been to that is hearing the cousin of a friend of mine describe his NDE, after he'd crashed his light plane in a wooded area, crawled clear as it started to burn, and leant against a tree while lying on the ground. He described the light, the tunnel, a sense rather than a vision of individuals present, and a general benevolence to it. He was unclear how it ended, but guessed he'd just passed out.
But he doesn't think he saw heaven &c. He thinks he experienced a kind of hallucination or illusion which the stresses on his body induced in his brain, though he admits to wondering at times.
I don't think he saw heaven either. The thing NDEs and OBEs have in common is that no one returns from them with new remote information about reality. I read of an experiment in a British hospital some decades back where two doctors placed placards in very large print on top of cupboards and fittings where they could only be seen from above, asking the observer to report the presence of the particular placard immediately. They had no reports for a respectable number of years, and finally gave up. OBEs can be induced 'in the lab' these days, as you may know.