I said I was going to comment on this in the Episode #692 thread, but the comment got way too long. So here's a full post.
In the most recent episode, a caller named Peter from New Zealand tried to prove that there is no God. Side comment: I have to say, I get really impatient with this topic, almost as much as attempts to prove that God does exist. Both pro- and anti-God arguments usually hinge on the notion that you can "prove" or "disprove" the existence of physical things through pure reason, without respect to the things that you actually observe in the universe. Augustine was really into this concept, and it was a big deal sometime around the Renaissance. But basically the rise of science was based on a recognition of the fact that our model of the universe is always going to be tentative, so we should build up a system that recognizes facts as more or less likely to be true based on their support through observation. There is never, ever, going to be some kind of successful argument purely of the form "A is A, therefore Bigfoot exists / doesn't exist." Proving things in the real world requires that you look at things in the real world.
Look, guys, 200 generations of philosophers have tried and failed to both conclusively prove and disprove the existence of God. If you think you have solved the problem all by yourself, you are most likely not only wrong but sounding completely ridiculous. Learn to live with uncertainty.
Peter in particular was making a fallacy which is extremely common in theistic arguments against scientific cosmology. Namely, he was making an equivocation fallacy on the word "universe."Early in the call, he says: "My definition of the universe is 'that which exists.'" That's fine, and it's certainly ONE legitimate definition of the word universe.
But as his argument unfolds, he wants to apply that same definition to the claim that "God created the universe." Then, the argument goes, obviously that is logically contradictory since God cannot create the universe if he is part of the universe.
To quote another caller: No, no, no, no, no. You're done.
The theistic claim that God created the universe applies to THIS, current, physical universe that we inhabit. That is a completely separate definition of the word "universe" from the one he started with. You cannot claim that you are using one meaning of a word, only to turn around and apply a different one. That's what the equivocation fallacy means.
Here, let Dictionary.com make this more concrete. Peter was starting more or less from definition #4 of "universe": "Logic: the aggregate of all the objects, attributes, and relations assumed or implied in a given discussion." I.e., "Universe" = "Everything." But "God created the universe" implies definition #1: "The totality of known or supposed objects and phenomena throughout space; the cosmos." That's not the same universe!
Let me put it another way. Science fiction and fantasy fans frequently refer to the "universe" that encapsulates a particular set of characters, history, and rules. For example, the universe of "Lord of the Rings" contains Middle Earth, Bilbo, Frodo, Gandalf, and all that deadly dull stuff in the Silmarillion. Fans of Joss Whedon's work refer to "the Buffyverse" (or sometimes "the Whedonverse") which contains the events of the Buffy the Vampire Slayer TV series and comic books, as well as Angel, and possibly (depending on how liberal you get) Dollhouse as well. Fans of David Weber's Honor Harrington character call his books the Honorverse. Etc.
Here's the point: J.R.R. Tolkien simply does not exist inside the Hobbitverse. Joss Whedon does not exist inside the Buffyverse. David Weber does not exist in the Honorverse. Certainly it is relevant and appropriate to speak about Joss Whedon during a discussion of Buffy, but Joss still does not occupy the same universe that Buffy does. (There are apparent exceptions, of course. But even if an author writes a version of him or herself into a story universe, it's still not really the author; merely a character who happens to bear the same name and some characteristics.)
In the 1977 movie "Oh God," George Burns appears as an unassuming man who turns out to be God. It is fair to say that in the universe(4) of "Oh God," God exists. It is also fair to say that within the context of that story, God created the universe(1). But you still can't confuse the two definitions with each other, and that's why Peter's argument is not good.
Within the universe of the fictional story known as "The Bible," there is a character called God. That character created the universe (i.e., the cosmos). I think we can all agree on this from a literary point of view. Christians only differ in the sense that they believe that the Bible is non-fiction, or in other words, we are living in a universe that is accurately portrayed by the Bible. If that were true, then God would exist within this universe(4) but not within this universe(1).
And now that I have beaten this topic to death, go forth and equivocate no more.