Dr. Craig is a liar.

[Pat Mustard]

It's pure unadulterated bullshit. First of all, atheists don't say there is no explanation for the universe's existence, most atheists follow the general consensus in science vis a vis the universe which is "we don't know how or why, or if their is any purpose, behind the universe's existence. But we may find out". Your premise a) would be like me saying that because some priests and ministers have molested children then SteveII condones the molestation of all children, and is obviously false.

Because a) is false, b) is an invalid conclusion.

None of what you said matters to asking the question whether the universe (or its predecessors) existed necessarily or contingently. Carroll seems to think neither--that the universe (or the quantum vacuum and its associated laws) always existed unexplained.

So, how is Carroll's view not: A) If atheism is true, the universe (or its predecessors) has no explanation of its existence.?

And that being logically equivalent to B) If the universe (or its predecessors) has an explanation of its existence, then atheism is not true.

B
I'll put it plain and simple, you asserting that somebody said or implied X does not mean they said or implied X, especially when, like in your current case, you've absolutely no evidence to support this assertion.

As I said your premise is pure bullshit, because it posits a unified mind for all atheists which is false, and then when you try to row back and lyingly claim you were talking about one man, you still managed to put words in another person's mouth.