Why are you chasing the idea of the existence of a God?

[Angrboda]

Naturally I believe the OP has a point. Do we have any clear evidence to point to the concept of God being totally limited to filling in the gaps of our knowledge?

The inability of theists to agree on even the most basic qualities is good evidence that it does not relate to a single, real entity. It's never been demonstrated that any of these versions do anything at all outside the mind of the theist. They generally do everything you'd expect, such as agreeing with them on every subject, and sharing their knowledge.

I'm not inclined to agree that this is a substantial issue. We have concepts without clear delineation that are nonetheless valid concepts, nobody complains that chairs don't exist because there is no all encompassing definition for what a chair is. We acknowledge the fallacy of the beard, that sometimes there aren't clearly definable distinctions without throwing up our hands and claiming that therefore all things belong in the same category. The concept of a beard doesn't become invalid simply because there is no clear dividing point. Language is by its nature slippery and trades on ambiguity for its power. That there is no clear and unambiguous definition of God even if true is a question of epistemology, not of whether such an ill-defined entity does or does not exist.

And I am still not convinced that spirituality  survives through indoctrination alone. I know of many people who become spiritual as adults who never grew up in a religious home.

Specific religions survive mostly through indoctrination. "Spirituality" can also mean virtually anything, and I agree, superstitious thinking can develop in adults.

Specific religions, doctrinally, sure. But the concepts on which religions are based? No. It's been determined that children spontaneously invent the concept of God. And the qualitative nature of having spiritual experiences is a basic fact of our psychology. Our minds have the basic tools and experiences and intuitions to come up with religion on their own. Indoctrination is, if anything, simply encouraging and giving shape to natural impulses. If it were true that religion were solely the result of indoctrination (and I realize you're not claiming this), then one would have to ask how it got started in the first place. Religion may be a bundle of falsehoods, but I think it's wholly natural.