Things that we are not aware of doesn't necessarily mean that they don't exist. There are in fact many things that do exist that we aren't aware of.My god, brahman, is satyam-jnanam-anantam’ (existence/truth-knowledge-infinity). The self and universe are known because of it. Not the other way around.
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Bonus point:
To me the question is wrong, as if the ego self is the progenitor and master controller of its cognition process. As if ego self is supposed to know of everything. And as if that which ego self does not cognise does not exist. That we are not aware of our own existence in sleep indicates that the presumption that what ego self does not cognise does not exist is wrong.
Note: I did not come up with the idea of bonus myself.
But since (if) your god didn't exist but we do, and still have the knowledge, how did we get that?