So, as I was watching Interview with the Vampire on Netflix and marvelling at how almost every trope of modern vampire fiction was done first by Anne Rice, something occurred to me when Louis mentioned not being afraid of holy symbols.
Imagine an Earth-like setting (obviously not D&D) where vampires don't care about holy symbols. Star of David, Star and Crescent, Flying Spaghetti Monster, they don't care. Religion has no power over them.
Except the primary Christian holy symbol. Why? Obviously not because Christianity is right about anything. The ichthys has no effect on vampires. No, vampires are bothered by crucifixes because they represent an instrument of execution and torture. The cross reminds the vampire of the death he doles out to everyone else, but can no longer hope for himself. Or something. (It's mythology, it doesn't have to make sense. At least, it doesn't have to make any more sense than the shaky justifications for arithmomania, inability to cross running water, lack of reflection, or distaste for garlic.)
Vampires have exactly the same reaction to nooses, guillotines, electric chairs, and so on. It's not symbols of religion that they care about, it's symbols of execution.
But part of that idea might just be how much I enjoy pointing out how morbid the use of the crucifix as a symbol is. Introducing a religion whose holy symbol is a noose would probably work just as well. In related news, I just had a brilliant idea about a new religion...