An imaginary conversation from the second chapter (Chapter 2: Can the Universe Create Itself) of The Mind of God: Science and the Search for Ultimate Meaning by :
ATHEIST: At one time, gods were used as an explanation for all sorts of physical phenomena, such as the wind and the rain and the motion of the planets. As science progressed, so supernatural agents were found to be superfluous as an explanation for natural events. Why do you insist on invoking God to explain the big bang?
THEIST: Your science cannot explain everything. The world is full of mystery. For example, even the most optimistic biologists admit that they are baffled by the origin of life.
ATHEIST: I agree that science hasn't explained everything, but that doesn't mean it can't. Theists have always been tempted to seize on any process that science could not at the time explain and claim that God was still needed to explain it. Then, as science progressed, God got squeezed out. You should learn the lesson that this "God of the gaps" is an unreliable hypothesis. As time goes on, there are fewer and fewer gaps for him to inhabit. I personally see no problem in science explaining all natural phenomena, including the origin of life. I concede that the origin of the universe is a tougher nut to crack. But if, as it seems, we have now reached the stage where the only remaining gap is the big bang, it is highly unsatisfying to invoke the concept of a supernatural being who has been displaced from all else, in this "last-ditch" capacity.
THEIST: I don't see why. Even if you reject the idea that God can act directly in the physical world once it has been created, the problem of the ultimate origin of that world is in a different category altogether from the problem of explaining natural phenomena once that world exists.
ATHEIST: But unless you have other reasons to believe in God's existence, then merely proclaiming "God created the universe" is totally ad hoc. It is no explanation at all. Indeed, the statement is essentially devoid of meaning, for you are merely defining God to be that agency which creates the universe. My understanding is no further advanced by this device. One mystery (the origin of the universe) is explained only in terms of another (God). As a scientist I appeal to Occam's razor, which then dictates that the God hypothesis be rejected as an unnecessary complication. After all, I am bound to ask, what created God?
THEIST: God needs no creator. He is a necessary being—he must exist. There is no choice in the matter.
ATHEIST: But one might as well assert that the universe needs no creator. Whatever logic is used to justify God's necessary existence could equally well, and with an advantageous gain in simplicity, be applied to the universe.
THEIST: Surely scientists often follow the same reasoning as I have. Why does a body fall? Because gravity acts on it. Why does gravity act on it? Because there is a gravitational field. Why? Because space-time is curved. And so on. You are replacing one description with another, deeper description, the sole purpose of which is to explain the thing you started with, namely, falling bodies. Why do you then object when I invoke God as a deeper and more satisfying explanation of the universe?
ATHEIST: Ah, but that's different! A scientific theory should amount to much more than the facts it is trying to explain. Good theories provide a simplifying picture of nature by establishing connections between hitherto disconnected phenomena. Newton's gravitational theory, for example, demonstrated a connection between the ocean rides and the motion of the moon. In addition, good theories suggest observational tests, such as predicting the existence of new phenomena. They also provide detailed mechanistic accounts of precisely how the physical processes of interest happen in terms of the concepts of the theory. In the case of gravitation, this is through a set of equations that connect the strength of the gravitational field with the nature of the gravitating sources. This theory gives you a precise mechanism for how things work. By contrast, a God who is invoked only to explain the big bang fails in all three criteria. Far from simplifying our view of the world, a Creator introduces an additional complicating feature, itself without explanation. Second, there is no way we can test the hypothesis experimentally. There is only one place where such a God is manifested—namely, the big bang—and that is over and done with. Finally, the bald statement "God created the universe" fails to provide any real explanation unless it is accompanied by a detailed mechanism. One wants to know, for example, what properties to assign this God, and precisely how he goes about creating the universe, why the universe has the form it does, and so on. In short, unless you can either provide evidence in some other way that such a God exists, or else give a detailed account of how he made the universe that even an atheist like me would regard as deeper, simpler, and more satisfying, I see no reason to believe in such a being.
THEIST: Nevertheless, your own position is highly unsatisfactory, for you admit that the reason for the big bang lies outside the scope of science. You are forced to accept the origin of the universe as a brute fact, with no deeper level of explanation.
ATHEIST: I would rather accept the existence of the universe as a brute fact than accept God as a brute fact. After all, there has to be an universe for us to be here to argue about these things!