From
http://en.wikipedia.org/wiki/Big_bang (emphasis mine):
"As used by cosmologists, the term Big Bang generally refers to the idea that the Universe has
expanded [not exploded] from a primordial hot and dense initial condition at some finite time in the past."
"Without any evidence associated with the earliest instant of the expansion, the Big Bang theory
cannot and does not provide any explanation for such an initial condition; rather, it describes and explains the general evolution of the Universe since that instant."
Questions on the initial condition aside, there is plenty of evidence showing that the universe is expanding. There is no evidence to suggest the initial condition was God or was created by God. Without positive evidence, the only appropriate answer to the initial condition question is 'We don't yet know'.