I hesitate even to put the words "God" and "vampires" in the same sentence lest anyone read the title by itself and not the following article. So please, read the article! :-)
It's an intriguing post on how the proof of the non-existence of vampires can be used accentuate the ridiculousness of some arguments used by agnostics, by application of the anthropic principle in negative form.
Joe Carter: "As I have stated ad nauseam, the uses of such an argument are not to prove that God exists but to highlight the metaphysical and illogical knots that the agnostically inclined will twist themselves into in order to deny the obvious. The fact that vampires don’t exist doesn't prove that God does -- but it does make that inference more reasonable and probable than its alternative."