Of course I believe that, but the writers of the vampires tend not to. In this age of political correctness, I'm sort of surprised I haven't seen a lot more "oh, it's not just Anglo-Christian religious symbols that set vampires to quaking in their boots!" sort of things, and I've read at least one novel in which a character claimed to be atheist, yet still raised no particular questions about why Christian holy signs repelled the vampires. I explain it in my head by saying "well, of course the Cross and churches and holy water are going to be repellent to a demonic force", but it's still strange in this anti-Christian era that the warding power of Christianity is taken for granted.

That philosophical enough for ya? :P

No! I want more Greek! And -- and mysterious signs on a chalkboard!