In a post at First Thoughts, Matthew Milliner quotes Terry Eagleton on the difference between creation as physical act and creation as metaphysical act:
For Thomas Aquinas... God the Creator is not a hypothesis about how the world originated. It does not compete, say, with the theory that the universe resulted from a random fluctuation in a quantum vacuum... God for Christian theology is not a mega-manufacturer. He is rather what sustains all things in being by his love, and would still be this even if the world had no beginning. Creation is not about getting things off the ground. Rather, God is the reason why there is something rather than nothing, the condition of possibility of any entity whatsoever.
While I wouldn't have thought this two weeks ago, before I heard the world's smartest man give the recipe for Cosmic Stone Soup, now I'm not sure "God is the reason why there is something rather than nothing" helps to clarify Eagleton's point.
To most people, the term "the reason why" implies, I think, an explanation, a denouement. If you know the reason why, then you know the whole story leading up to something, and you also know that other possible explanations aren't the reason why.
As Eagleton says, though, God as Creator is not a competing theory to quantum vacuum fluctuation. He is "the reason why" in a completely different sense than quantum vacuum fluctuation could be, and since Hawking & Co. don't understand this, it might be better to avoid using a term that has a perfectly legitimate meaning in science.
Moreover, it could even be said that "God is the reason why there is something rather than nothing" isn't strictly true, in that the bare fact that God exists doesn't explain why the universe exists, while Hawking's proposal is that the bare fact that the law of gravity exists does explain why the universe exists. It is (if I may slip unnoticed from hacked up philosophy to hacked up theology) only through a perfectly free act of will that God created the universe. To say "God is the reason why something exists" is akin to saying "my wife is the reason why there's a jar of pickles in the oven." They both say who (or Who) is the cause, but neither says why the [C/c]auser caused something.
Lacking a better thought, I'll suggest we go with the tried and true "God is the First Cause of everything." Granted, "the First Cause" is capable of being misunderstood as the initial member of a sequence of causes, but I'd still guess it sounds odd enough to most people that they wouldn't automatically assume they knew what it meant.