A popular response to the idea of a God as the ultimate final explanation for all things is to ask, “Who made God, then?” It’s always hard to know how seriously the question is being put forward.
For example, seriously asking the question presumably accepts temporarily the idea of some kind of God existing. Does the questioner provisionally accept polytheism, henotheism, pantheism, or other forms of theism? My guess is no, and that the questioner intends the question as some kind of logical proof (??) that a god is not (or cannot be?) a final/ultimate explanation for all things. Which leads me to my other point…
Asking the question sets up a regress of explanation in which each god postulated for an explanation requires yet another god, which requires yet another… ad infinitum (much similar to the ‘Turtles all the way down‘ story). This explanatory regress is, quite literally, infinite, and it seems to me to be instantaneously obvious that — unless one wants to postulate an infinite number of gods/explanations — the infinite regress points immediately to an infinite God (worthy of the capital ‘G’) as the fount/origin/source/beginning-and-end of all explanation (not to mention existence).
So, the ‘who made god’ question — to my mind — is really an attempt at creating an explanatory need for something that was intended as a final/ultimate explanation anyway.