But of course the claim that the universe came from nothing can also be understood as the claim that the universe did not come from anything. Here, I want to consider this interpretation further (since for the most part I ignored it last time around). As it turns out, these two ways of interpreting “nothing” lead to results that are as different as they can be.
To better explain things, I'll use a means I haven't tried before, that of an imaginary dialogue between a theist and an atheist:
Theist: “Atheism is obviously false, since it claims that the universe came from nothing. But nothing can come from nothing!”
Atheist: “But atheism doesn't claim the universe came from nothing – at least not in the way you obviously mean.”
Theist: “Well, if there's no God, what did the universe come from, then?”
Atheist: “Nothing.”
Theist: “Ha! You're contradicting yourself! You just said atheism does not claim the universe came from nothing!”
Atheist: “What I mean is that the universe did not come from anything. There isn't anything from which the universe came.”
Theist: “But that's what I'm claiming is impossible. If what exists did not come from anything, then it came from nothing. But if you start out with nothing, then how can something ever arise? Answer me that!”
Atheist: “Not coming from anything is not the same as coming from nothing, if by that you mean from a prior state of nothingness. In fact, the latter is necessarily false and thus impossible, whereas the former is necessarily true – and therefore the only possibility.”
Theist: “Well, at least I agree with half of that: the latter is impossible. As I've said, if you start out with nothing, you will never get something.”
Atheist: “That's not the reason I say it's impossible. It's impossible because the claim that you 'start out with nothing' is already problematic, as it implies that at some point there existed a state of nonexistence. It also implies that there was a state before there was time. For these reasons, the claim that the universe arose out of a prior state of nothingness is necessarily false.”
Theist: “But if you think that, why do you claim that the universe did not come from anything? The two sound the same to me.”
Atheist: “When you ask 'where did the universe come from if there's no God?', you're really asking 'where did everything come from if there's no God?' But now, since in that case we are talking about everything that has ever existed or ever will exist, there is by definition nothing else – and therefore nothing else for it to come from. It follows that the universe did not come from anything. And that is the case whether the universe has existed for an eternity or began existing some finite time ago. Either way, it did not come from some prior state; it simply exists. So, at the risk of being misunderstood, from now on when someone asks me whether the universe came from nothing, I'm going to answer 'Yes – anything else is impossible!'”
Theist: “Well, I still maintain the universe could not come out of nothing. What I believe is that God created the universe out of nothing!”