For those who are already committed to believing that naturalism is true, then of course God cannot exist. Stokes quotes from scientist Lee Smolin:
It is true that the universe is as beautiful as it is intricately structured. But it cannot have been made by anything that exists outside it, for by definition the universe is all there is, and there can be nothing outside it. And, by definition, neither can there have been anything before the universe that caused it, for if anything existed it must have been part of the universe. So the first principle of cosmology must be "There is nothing outside the universe."One way to show that God does not exist is to assume the impossibility of his existence. Here, naturalism assumes that nothing can exist outside the universe. Ok...can you prove that? No. It is a presupposition.
Another approach to proving God does not exist is to assume that people believe in God as a source of explanation. How else can we explain this "beautiful" and "intricately structured" world? If science can show that there's a perfectly natural explanation for the universe, then this would remove the reasons for believing in God. This seems like a reasonable argument, but it falls short because - for the vast majority of people - they don't believe in God because his existence provides the best explanation for the world and everything in it. It's mostly quite the opposite: People already believe in God and, therefore, he becomes the source of explanation of the universe. Scientific theories that challenge my beliefs may cause some consternation, but I'm not going to abandon my believe in God because God is not fundamentally a scientific hypothesis that is subject to inference. It is the result of a personal revelation and relationship with him. Credo ut intelligam: "I believe so that I may understand" not "I understand in order that I may believe."
And even if scientists like Hawking were entirely successful in their arguments, the most they may be able to show is that it's not impossible that God didn't create the universe. They offer an alternative explanation. OK. But an "it's not impossible that God didn't create the universe" argument is not that impressive. Hardly a slam dunk.
To end this chapter, Stokes poses a "what if": What if science can show that it can explain everything and that there is no being such as God. It is nowhere near accomplishing this, but Stokes concedes the point for sake of argument. Suppose Hawking and friends are right. What follows from this?
In the last part of the book, Stokes explores the state of morality in a world without God.