What if God was proven to have never existed?

[Simsim]

But can you disprove the existence of an entity define as being non-corporeal, non-physical, which is everywhere at the same time, and created the Universe we inhabit?
Can you disprove that the flying spaghetti monster exists in the unbounded non-physical space of whatever it means to be "outside the Universe"?

I read many objections against the God existence but I think all of them can be confuted ( I myself spent years debating them when I was a believer )
But we can easily prove the holy books imputed to him to be wrong and just human inventions. Thus the God idea will have no application and his existence will be equal to his non-existence.
If your assumptions or theories can't be testable or proven right or wrong they primarily will have no value.
For religious people, as I think, it is better to confute their religions not the existence of God. Debate what they impute to the creator not their creator himself. After it will be obvious to them that their religions are human inventions and can't be credited to an infallible being they, themselves, will take the next step and look at their god as just an assumption not as an absolute reality.