I consider Steven Hawkings one of the most remarkable men of our generation. He is a medical miracle, having survived with Lou Gerig's disease for over 40 years. In spite of his condition, he is regarded as the most brilliant theoretical physicist of our time, and has been compared with Albert Einstein. He earned this reputation because of his description and explanation of black holes.
One of the reasons that we are familiar with his name and career is that he is also a popular writer. He has taken his theories and sought to explain them to the general public by writing two significant books for the mass market. In doing so, he has sought to give a non-supernatural explanation for the cosmos.
In his first book, he attempted to explain the current theory of the origin of the universe called the Singularity. The Singularity means the universe we live in is not eternal, and this has serious metaphysical and theological implications. Rober Jastrow's famous quote about science confirming theology comes to mind. In order to explain the fact that our universe is not eternal and yet could still be the result of purely natural causes, Hawkings had to resort to quantum theory. He concedes that before the Singularity (Big Bang) nothing of this universe existed. His claim is that the quantum level of negative energy was exactly equal to the quantum level of positive energy thus producing zero actual energy. This condition of "zero" matter/energy had to have existed for an eternity of past time until, as some cosmologists try to explain it, this state was disturbed by a "quantum fluctuation" that destroyed the balance and produced the Big Bang.
Without getting too deeply in over our heads, it is important that we apply some simple logic to these questions. J.P. Moreland has pointed out that "nothing" is no thing, it is not positive and negative energy states that cancel each other out. If "nothingness" ever were the condition of the universe, then we wouldn't be here. You can't get something from nothing.
Hawkings is using a high degree of theoretical speculation in his claim, for which there are some serious unanswered questions. First, "where" was this massive amount of energy located, and how did it break through to literally create our universe? Second is the problem of equillibrium. If the "stuff" of the universe has existed forever, as naturalism requires, then it long ago reached a state of equillibrium (we're dealing with eternity remember). Equillibrium means nothing happens unless something from the outside acts upon it. How this something acted and/or what caused it is the significant dilemma that naturalism faces in explaining the origin of the universe.
In his latest book, Hawkings has gone evern futher, based on string theory, he stated that the existence of gravity provides the capacity for the universe to create itself. In other words, he is assuming that gravity exists as the ordering principle for the emergence of a universe capable of sustaining life as we know it. In terms of the current theories of galaxy formation, etc. such a claim makes sense in describing our sun and even planet earth. I have to assume that he and other naturalistic thinkers feel that if they can find an explanation for the development of the chemical chart and the planets they have done their job because evolution takes over from that point.
As someone who doesn't accept the "theory" of evolution, I find that assumption more of a leap of faith than a fact of science. The existence of hydrogen, carbon, oxygen, and nitrogen do not DNA or life make, and gravity has no capacity to change that fact. It is at this level, the crucial level of organization from non-living matter to life that I found most outrageous in his claim. To be fair to him, he is making the assumption that I described in the last paragraph. He is assuming that the development of life is "automatic" given the pre-historic conditions on earth and that evolution is a self-evident fact of nature.
The level of complexity is still, and will continue to be, the problem for these naturalistic theories. I often think of Stephen J. Gould's attempt to make the comparison between the chance development of life and winning the lottery. Such a comparison would work if there were just one chance event that had to take place to produce life as we know it, but there are billions of events (at least) for which the chance explanation completely breaks down. We can be lucky once or twice or even ten times, but not billions of times.
While Stephen Hawkings is a brilliant theoretical physicist, his explanation of the origin of the universe needs to be taken for what it is, an attempt to provide a naturalistic explanation for the universe. As such, it faces the same problems as all naturalistic explantions, the universe is too complex to be accidental. While gravity is a remarkable force, it has no capacity to take the place of our Creator.