I know what you are saying and I am not certain about the physics. I do think though it can be complicated by the fact that how we conceive of matter isn’t necessarily the same as what a physicist means in the sense that matter of our everyday experience is only one form of matter whereas there are others…So it might be complicated by that fact.
Even if you are right, what Hawking might have been saying is that gravity helps us understand how the beginning of the universe occurred naturally, that is, without any need for a miracle. Gravity might be simply resolving certain theoretical difficulties about the nature of the big bang. I am not sure, this is all said as speculation
Yes, quantum gravity will potentially help us understand how the universe began. There is a lot of mystery surrounding the big bang, why it happened, and certain other physical puzzles about it. QG is a theory, not directly related, which gives us a description of gravity in terms of quantum mechanics. With this in place, we would presumably have a better description of the universe in its early moments. But how the universe began doesn’t tell us much about why it exists. That would be like pointing to the first chapter of a story to eliminate the need for an author.
What must be understood also is this:
science simply does not have the tools, no matter what it discovers, to show God is not necessary.
Traditionally, theism asks three main questions:
- Why are there contingent things?
- Why is there intrinsic order/intelligibility to our universe?
- Why are there transcendent things like goodness or beauty in our world?
These questions are posed in various ways, articulated in the forms of various arguments. Obviously 3 has nothing to do with science. The first one, science can’t answer because you can’t invoke contingent things (what science does, whether they be laws, objects, events or whatever) to explain why contingent things exist. The second one, science can’t give us an answer because you can’t explain intrinsic order or rationality to the universe by appealing to further examples of intelligibility or order in the laws of nature. So science has no power to discredit these traditional philosophical questions which have led people to believe in God.
If Quantum Gravity is true, we must still ask, why there is a physical system such that it is governed by QG in the first place.
These links may be helpful:
catholicxray.com/creation-god-the-author/
edwardfeser.blogspot.com/2013/07/fifty-shades-of-nothing.html
reasonablefaith.org/contemporary-cosmology-and-the-beginning-of-the-universe (although this link is trying to defend the beginning specifically, something which I don’t think is particularly useful in proving God)
catholicxray.com/proof-of-god-and-the-laws-of-physics/
edwardfeser.blogspot.com/2010/12/dreaded-causa-sui.html
I am not sure what you mean by the second part of this question.