When people say there's nothing before the big bang, they either got it wrong or do not mean nothing. As Dr. Krauss points out, vacuum, alas nothing, is not nothing, it is something. It is the universe's default energy level. From this the big bang could be initiated and appears to exist from "nothing".

Whether or not God came from nothing depends on your view of God. Since God is not very well defined in the first place; many religious people will give different answers if you ask what God is; it does not qualify to be (dis)proven by empirical experiments. Any individual answer can be verified, but if the facts keep shifting from man to man you can't come with a general conclusion for God's existence anyway.

But if you ask an astronomer what the big bang is, they all should give the same answer.

So if God came from "nothing", like the big bang, it means God was created by conversion of energy to matter/structural patterns ( if that is possible at all ), but that would be disputed by many religious people, since God wasn't created!

It's not like there are no answer to think of to hypothese God's existence, it's just that religious people wont acknowledge any of them.


EDIT: what AlbertoT says.