I found that, on the contrary, many Christians disbelieved the whole Big Bang idea and adamantly opposed it. Strange.
More recently, I have come to realize that the Big Bang is not actually a theory of how the universe began; rather, it is a theory of how the universe has changed over time. It is astounding that we can now describe the history of the universe back to 13.7 billion years ago, when it looked dramatically different than it does today. But if you try to push back further, then we have every reason to believe that our theories break down, and no reason to trust their predictions beyond a certain point.
The idea that the universe began in a singularity, which was also the beginning of time itself, is really no part of the Big Bang model (though it continues to appear in popular presentations of the theory).
This point is made in a well-thought-out paper by Hans Halvorson and Helge Kragh. (Hat tip: ex-apologist) They make a lot of other good points, too, and the whole thing is worth a read, but I was particularly struck by one thing. They ask what would happen to the theist's argument for God from the Big Bang if the theory were disproven. Would the failure of the Big Bang undermine theism? Of course not! Even if we knew the universe existed prior to the (moment we refer to as the) Big Bang, the theist could claim that God had created the universe at an earlier time, or that God had created an eternally existing universe. Then they say:
The point is that insofar as the failure of the big-bang model would not undermine theism, so the success of the big-bang model does not support theism.
This, I think, is a very important point. And it is one that is devastating for many of the conventional arguments for God.
The basic principle is this: if X is evidence for God, then ~X ("not X", the negation of X) must be evidence against God. Or to put it another way, if X and ~X are equally consistent with the God hypothesis, then neither of them can provide an argument for God.
Swinburne, for example, claims that the constancy of physics across time and space is evidence for God. Why does an electron here on earth have the exact same mass, charge, and spin as an electron in a distant galaxy? This constancy calls out for an explanation (says Swinburne) - and the explanation is God.
But suppose that one of the many experiments looking for changes in the fundamental constants was successful. Suppose, for instance, that we found the electron's charge was changing over time. Would Swinburne take this as evidence against God? I suspect he would not. But if the God hypothesis is equally consistent with constant electric charge or changing electric charge, then constant charge cannot be evidence for God.
On a larger scale, theists often ask what is the origin of natural laws themselves. But if regularity in the operation of nature is evidence for God, then lack of regularity - randomness - in its operation must be evidence against God. And quantum mechanics shows that, at the most basic level, nature is random and unpredictable. So quantum mechanics is evidence against God!
I don't really think that quantum mechanics is a good argument against God. By the same token, I don't think the regularity of physical laws, or the constancy of particular physical parameters, or the Big Bang singularity (if there was one), are evidence for God.