I know a lot of religious people like to bring up this question; somehow mistakenly believing this is some kind of trap for a rational mind that follows science more than faith.
The interesting part is it is just as much a "trap" for religion as it is for science. The same logic of something could not come from nothing apply as much to god as they do to the singularity from which the big bang emerged.
If nothing cannot create something, then where did god come from? How did he create the universe? Not only would he have to have been "created from nothing" but so would everything else... as he had nothing to create them from other than NOTHING.
If god is capable of just always having been here, then so is the singularity. It could have just as easily "always have been here; no time in which it was not present." If god can just magically manifest himself from nothing one day, then so can the singularity.
The bottom line is ANY rationality you use to explain why god can bypass the "something cannot come from nothing" rule can just as easily be applied to the singularity. Of course, this also works in reverse. *cont*
How funny that mankind assumes that all questions can be answered through our extremely limited accumulated knowledge base. And how predictable was it for man to create a diety to explain the "unexplainable". We are simply animals with enough intellect to question our own existence and fate. But unfortunately, we are not smart enough to answer those questions.
So god was created, and millions of people have died and will continue dying for what ends up being a way to alleviate our fear of the unknown. I refuse to live in a world of basic thought, where fear dictates reality and man is reduced to a sheep.
Educate yourself instead, here's a possible answer to your question that is based on fact, not superstition. I bet you don't even watch it, house of cards and all that.