To discuss the existence or nonexistence of something like God or gravity is meaningless. What matters is whether the concept usefully describes what we experience. Gravity is valid concept because it accurately describes the behavior of objects of mass. But arguing about the actual existence of gravity is basically philosophical nonsense. The same applies to God. As gravity describes objects of mass, God describes societies and cultures. And God is a valid concept for the same reason that gravity is a valid concept, because God does accurately describe what we know about history. And now I have suggested a way of experimentally validating this. How long will you let your blind faith in Atheism prevent you from seeing the facts?
I hope you don't mind if some random guy jumps in sir, I apologies if you do.....
However I must point out that if your point about God being a useful concept is true based upon its ability to explain is to be taken seriously then the word God must mean something.
The primary attribute (essence) of God is usually the various omi's (all powerfull all knowing etc.)
I'm sure you have seen how these potentially contradict, likewise im sure how you have seen people make the claim that God's true nature is unknowable as well.
This poses to problems that brender the word God potentially cognitively meaningless:
1: incoherence- "I was drawing a squiangle" (defined as a 3 sided square) doesn't tell me what im drawing because the idea of a squiangle is literally unthinkable.
2. Undefined essence- If God's essence is unknown then we are unable to ascribe meaning to the word God.
For example: I can see a chair in a dark room, I can't tell what color it is but i can see its a chair. I know what word corresponds to the idea of chair thus I have the means to tell you there is a chair in the dark room.
If however I cannot tell its a chair and can only see its red I cannot have knowledge of the chair and therefore cannot tell you of the chair.
If God exists outside of our cognitive ability to understand him then we may not use him as a means to explain anything at all.
For the word God would have the same level of meaning as the word Blark. (Which isn't a word in English in case your not a native speaker.)
In situation two God would be just a noise not a word.
I'm not accusing you specifically of having a bad definition, as I have yet to see you provide one for God, I however wish to challenge you to provide one that is cognitively meaningful and does not render God trivial like that of a naturalistic pantheist's God.