Recently, I was watching a debate on television between an atheist and a believer. The Christian had presented several arguments to support the idea that the physical universe of space, time and matter had not existed forever, but rather came into existence a finite period of time ago. He went on to argue that the best explanation for this fact is that there is a First Cause — God — who caused the universe to come into being.
At that point in the debate, the atheist responded, "If you say that everything needs a cause and so there must be a cause for the beginning of the universe, then what caused God? And if you say that God is the first cause and nothing caused Him, then why not just say that the universe itself is the first cause and nothing caused it? Postulating a God is both unhelpful and unnecessary."
Fortunately, the believer was prepared to give an answer to this response, but would you have been ready? What would you say if presented with this argument? Let's see if we can make some progress in formulating an answer.
There's Something Fishy with the Question
The first thing to notice is that there is something wrong with the question, "Who or what caused God?" To understand the problem, I need to introduce a simple notion in logic called a category fallacy. A category fallacy is the mistake of ascribing the wrong feature to the wrong thing. For example, asking, "How many inches long is the smell of a rose?" or "What does the note C taste like?" seems to assume that smells have length and sounds have taste. Both assumptions commit a category fallacy.
You can commit a category fallacy about something even if that thing does not exist, as long as you have a concept of what the thing would be if it were to exist. For example, unicorns do not exist, but we have a concept of what a unicorn would be if it were to exist, namely, a one-horned horse. Given this concept, the question "How many iron filings does a unicorn attract?" commits a category fallacy (it falsely assumes that unicorns have magnetic properties which, given our concept of a unicorn, is a confusion of categories).
Now, the question, "What caused X?" can only be asked of things that by definition — by their very concept — are causable sorts of things. I can ask, "What caused the Earth to come into existence? What could cause unicorns to exist if there were such things? What caused the universe to come into existence?" because all these things — the Earth, a unicorn, the universe — are things that by their very nature have, in fact, come into existence. So it is not a mistake to ask a question about what caused something if the object itself is the sort of thing that could be, or in fact, was caused to exist.
Now the universe could not be the First Cause. Among other things, the Big Bang theory is still the most widely accepted view of the origin of the universe, and it entails that the universe came into existence, a fact that disqualifies it from being the First Cause. The universe is like a borrowing lender. By contrast, an immaterial, spaceless, timeless being is the proper candidate for such a First Cause. And while I cannot argue the point here, it should be obvious that the God of the Bible satisfies this description of the First Cause. In any case, it is a category fallacy to ask of the First Cause what caused it. Otherwise, it wouldn't be first.
But the very concept of God in the world's monotheistic religions is a concept of a necessary being, "the uncausable Creator of everything else." Given this concept of God, the question "Who or what caused God?" becomes this question: "Who or what caused something which, given a widely shared concept of God, whether He exists or not, is an uncausable thing?" Or more briefly, "Who caused God which by definition is uncausable?" It is a category fallacy to ask about the cause of something that by definition is not causable. You can only ask such a question of causable things. So the question, "Who caused God?" is like the question "What does the note C taste like?" It's a pointless mistake.