When I lost my belief in God, the near-universal reaction from my Christian friends was to sweep a hand at the marvelous world around us and say, “Where did all this come from, then?” For them, God was the only possible explanation.
Among scientists, the hypothesis that our universe was born from a larger multiverse has steadily been gaining credence. There are several ways this could be true. As one possibility, the Big Bang could have been a quantum fluctuation in another universe, which in turn could have been born in the same way from its parent, stretching back forever. With this model, the multiverse is like an eternal froth of bubble universes. There are other models, too. I recommend Brian Greene’s book, The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos if you’re curious.
As an answer to “Where did all this come from, then?” the multiverse model may seem to be on equal footing with “God did it.” By definition, we cannot reach out and touch other universes to prove they (and therefore a multiverse) exist, much less can we prove that our universe arose from the multiverse by some natural process.
It’s true that we can neither prove that God did it, nor that the multiverse and the laws of physics did it. But as I outlined last time, just because competing explanations are uncertain does not mean they are on equal footing.