besides seeming absurd to the layperson, the infinities of the big bang singularity have always made physicists and cosmologists a bit uncomfortable. infinities in physical calculations have always tended to be indications that we've been doing something wrong.
string theorists explain that we can avoid the infinities using superstring theory which posits than nothing can be smaller than the planck length, or more correctly, if anything WERE smaller than the planck length in the familiar visible dimensions, it would stretch out in all those other invisible dimensions they love to talk about, such that the physical properties of the pre-planck universe would kind of flip over such that you couldnt tell them apart from the universe we have now.
classical physicists think string theorists have just been playing too much Quake but this is kind of a compelling idea because it eliminates the infinities, the infinitely small, infinitely hot. kind of the way special relativity eliminated the infinity of speed. not by putting a speed limit at light exactly, but rather showing that anything that WAS going faster than light would really be going slower than light, but backwards in time. its the same kind of cyclical pattern
anyways string theory is all a bit esoterical. if you want to take a crack at trying to understand this better than myself, try brian greene's The Elegant Universe.
Personally i think all such beginning of the universe discussions are so theoretical and speculative that, while fascinating, they are not really useful for questions of philosophy or theology.
mox