I've never seen a definition of 'god' or 'God' such that if we found a candidate, we could tell whether it was a god / God or not. In fact all the definitions carefully avoid making 'god' real, and call [him] 'spiritual', 'immaterial', 'incorporeal' and so on. The trouble with those adjectives is that there's no objective test that can distinguish the 'spiritual' or the 'immaterial' (&c) from the imaginary.
I must salute you, good sir. This paragraph <above> is one of the most concise descriptions I have read in a very long while, which neatly explains the conundrum we humans face, with respect to the "god" question.
I have elsewhere, asked theists this basic question many many times: please define your god, so that we may further examine it's characteristics to determine validity.
They seldom do, as a defined thing may be tested against the defining criteria, and as often as not, shown to be an impossible construct. Not unlike the traditional impossible thing: a square circle.
Whereas an undefined thing, I have pointed out frequently, really has no substance; nobody truly worships an undefined thing, even if they won't admit it.
But even if there were some who did, an undefined god has the delightful characteristic of having no commands the followers must impose onto other folk. So we can safely ignore such things with no real consequences.
As far as my research has discovered, nobody ever blew up a building, nor even punched someone in the snoot, on behalf of an undefined deity.
No-- such activities are always in the name of very clearly defined gods, usually from some ancient book or other.
And those? We can test for reliability. So far? All such tests are either ambiguous (no different from pure random chance), or the test conclusively shows said deity is unresponsive.
I've raised my cuppa coffee to your comment.