For Judeo-Christianity, God is not a person in the sense that Al Gore arguably is. Nor is he a principle, an entity, or ‘existent’: in one sense of that word it would be perfectly coherent for religious types to claim that God does not in fact exist. He is, rather, the condition of possibility of any entity whatsoever, including ourselves. He is the answer to why there is something rather than nothing. God and the universe do not add up to two, any more than my envy and my left foot constitute a pair of objects.
This, not some super-manufacturing, is what is traditionally meant by the claim that God is Creator. He is what sustains all things in being by his love; and this would still be the case even if the universe had no beginning. To say that he brought it into being ex nihilo is not a measure of how very clever he is, but to suggest that he did it out of love rather than need. The world was not the consequence of an inexorable chain of cause and effect. Like a Modernist work of art, there is no necessity about it at all, and God might well have come to regret his handiwork some aeons ago. The Creation is the original acte gratuit. God is an artist who did it for the sheer love or hell of it, not a scientist at work on a magnificently rational design that will impress his research grant body no end.