One God or billions of universes?

Physicist Stephen Hawkings says that there is no need of a deity to have created the universe.  Instead, according to this review of his new book, he posits the existence of billions of universes, at least one of which (ours) happens to have the physical laws that would allow for life.

With that background [a survey of the history of physics], Hawking and Mlodinow get to the real meat of their book: the way theories about quantum mechanics and relativity came together to shape our understanding of how our universe (and possibly others) formed out of nothing. Our current best description of the physics of this event, they explain, is the so-called “M-theories,” which predict that there is not a single universe (the one we live in) but a huge number of universes. In other words, not only is the Earth just one of several planets in our solar system and the Milky Way one of billions of galaxies, but our known universe itself is just one among uncounted billions of universes. It’s a startling replay of the Copernican Revolution.

The conclusions that follow are groundbreaking. Of all the possible universes, some must have laws that allow the appearance of life. The fact that we are here already tells us that we are in that corner of the multiverse. In this way, all origin questions are answered by pointing to the huge number of possible universes and saying that some of them have the properties that allow the existence of life, just by chance.

via Review of ‘The Grand Design,’ by Stephen Hawking and Leonard Mlodinow..

As some of you readers never tire of reminding me, I don’t always grasp what the scientists are saying.  Can anyone explain this multiple universe theory?  Specifically, what is the evidence for it (or is it just a theoretical construct)?  Isn’t it just a way to account for the fine-tuning of the universe for life without having to believe in God?  And isn’t it more rational and a better application of Ockham’s razor (when in doubt, choose the simplest solution) to believe in a Creator?