The Big Bang theory never said otherwise. It just says everything in the universe was in a singularity and then it expanded.
No it doesn't.
The Big Bang theory says nothing about what was "before" the singularity or even if it was a "before". Your speculations have nothing to do with the Big Bang theory.
Don't you ever get tired of repeating over and over again that nothing can be added or taken away? Will you ever get it into your skull that the Big Bang theory says nothing about anything added or taken away but that what existed just expanded?
I pretty much said the same things to Ben.
I kept telling him, that the Big Bang only concentrate its theory largely on the observable universe, with some hypotheses of earlier epochs after the initial expansion (BB).
Ben keep distorting the theory, no matter how many times I have said that's now what the Big Bang say. He keep bringing up the "eternal universe" as if it factually truth, but this is pure speculation. And yet he persisted.
My replies seems to bounce off his eyes, so that he is not registering anything I have to say, which is why I've pretty much given up explaining to him in this thread.
He doesn't understand that the Big Bang don't talk of before the singularity, and he keeping bringing up other cosmologies that have nothing to do with the current BB theory.
The only newer and major contributions to this theory, is that the dark energy is causing the acceleration of the universe expansion, beside from the better images of Cosmic Microwave Background (CMB) radiation from recent space telescope(eg WMAP).
CMB radiation is the primary evidence for the Big Bang cosmology, first predicted by Alpher and Herman (along with Gamow), in 1948, but first discovered in 1964, by Penzias and Wilson.
Basically, the CMB is the earliest photons (light) we can observed, which occurred during the Recombination epoch, starting 377,000 years after the Big Bang.
Other hypotheses and other theoretical theories have been around for some times now, but these are currently untestable and speculative, like the eternal universe (professed by Ben, of course) and the multiverse models favoured by others here.
For me, as far as I understand the Big Bang theory, it doesn't say that the universe came from nothing, but that doesn't mean it is an eternal universe. We just don't know, because we currently can't observe beyond the "observable universe".