From Professor Edgar Andrews’ forthcoming book Who made God?:
It’s a question commonly posed by those who would banish the very ideas of God and "creation". Richard Dawkins asks it repeatedly, in various ways, in his best-selling book The God Delusion. The logic runs something like this.
If God exists, then presumably he created everything (why else would we need him?) But if God exists, who made him? And since no one can answer that question, it does nothing to solve the riddle of the universe to say "God made it". We simply push the mystery one step further back and that is a pointless exercise.
No one can doubt that atheists regard their "unanswerable question" — "Who made God?" — as a formidable weapon in their war against faith, but there is more to the question than meets the eye and it crops up in a surprising variety of philosophical contexts.
So let’s look briefly at three such contexts — the "we made God" hypothesis, the "improbability of God" calculation, and the "unanswerable question" dilemma.
... missing out discussion about the first two ...
The third context in which "Who made God?" appears is the most obvious one. The question is deemed unanswerable because the only realistic reply is "no-one made God". And if no-one made God, then he can’t be there, can he? After all, for every effect there must be a cause. An effect that has no cause must be imaginary.
Once again, in their enthusiasm to prove their point, the proponents of this argument entangle physics with metaphysics. Cause and effect do indeed reign supreme in the physical realm — both science and normal life would be impossible unless they did. But why should they operate in the same manner in a spiritual realm (if such exists)?
We have a choice. Firstly, we can assert a priori that there is no such thing as a spiritual realm — that nothing exists that is not physical and open to scientific investigation. On this basis we can proceed to claim, with some logical justification, that every possible effect must have a cause, because that is how the physical world works.
But what we cannot do is use this claim to disprove the existence of God on the grounds that he doesn’t have a cause! Why not? Because our argument would be completely circular. We begin by assuming that no spiritual realm exists and conclude by "proving" our initial assumption. Big deal.
So let’s try to find a different route through the maze, this time without cheating. To avoid assuming at the outset what we want to prove, we must start by allowing that there might indeed be a spiritual realm.
Because cause and effect is only proven for the physical world, we can no longer insist that they are relevant to the origin of a spiritual entity like God. Therefore God doesn’t have to have a cause — he can be the ultimate uncaused cause, a being whom no-one made.