You're asking where did X come from if not from a creator. If not from a creator X would have to have come from a source that wasn't a Being. I don't know how to justify this. X being made by a being who created it seems to make the most logical sense to us as humans, from our limited vantage point. Could it logically have been something else? I don't know if we yet have the answer to this.

Philosophy is justified by logic, is it not? And logic needs no justification.

An omnipotent God that's still bound by the rules of logic does not have to be unknowable, as a result. Just because he could do anything doesn't mean he would exhaust even a fraction of the possibilities of what he might do, if it isn't in accordance with his temperament or character.