[Ono-Sendai]

The big bang theory explains a lot of stuff, like the cosmic microwave background, and the redshift of far-away galaxies.

[collyw]

Its usually given as an answer to "where did the universe come from".

[renox]

Only by ignorant people.. The more knowledgeable one will tell you that the big bang is the description of the state of the "young" universe but that we don't have the tools to describe/know what was before/what created it (yet).