Coming out of lurk mode to say that this conversation can be had without insults. It is an interesting topic regardless of one's beliefs, or lack of. That said, I think that the movie Twilight isn't the best example here. A better one is the show Being Human. The entire premise is based around these monsters, through no fault of their own (each was attacked and got their "curse", "virus" or whatever) have to come to grips with the fact that they are monsters, all the while trying to preserve their sense of humanity. At some point, they feel as if God has abandoned them and they feel that they shouldn't fight their natures, and simply give up trying to "be human" and march to the devil, willingly. But that small spark of their humanities always seems to trump that.
This story, while fiction, makes me think about the very human struggle that all people have in their day-to-day existences. For some, the monsters are all to real. They come in the form of rapists, molesters, child abusers, cheating or abusive partners and murderers. Some of these criminals actually worship God, are Christians themselves. How did they get to the point where they abandoned the Divine within them to do the most heinous acts against innocents? I hardly doubt it was because they learned about pagans and druids, or watched Harry Potter or Twilight. Evil in humans has always existed. Fiction based on humans will always exercise the fight between good and evil. Some may feel their children need protection from such stories and that is a parent's right to make that call. But they must also be aware the evil in the world exists whether or not there ever was a Jk Rowling, Stephanie Meyer or even Shakespeare, for that matter. A peek at the evening news will attest to this.
It is a fact that pagan beliefs preexisted Judism, Islam and Christianity. An excellent film about how pagans, Jews and Christians once got on together then began to fight against each other is Agora. The fights are sort of a subplot, the main story is about the female philosopher Hypatia and her being the first to put forth the theory that the planets orbit the sun in an elliptical path versus a circular one. She was labled a witch and put to death. Thousands of years later, a man named Kepler took credit for Hypatia's theory.
Factoid about vampires: The only thing close to an actual vampire in real life was the Transylvanian countess Bathory. She was in her late thirties and fell in love with a man in his early twenties. He was betrothed to another, so Bathory had her maid, a witch, make up spells and charms to keep her beloved, as well as to help her keep a youthful appearance. One day, another maid was brushing Bathory's hair and hit a snag, hurting the Countess. She struck the maid and drew blood. Some of that blood landed on the Countess's face. In a deluded state, she swore that the young maid's blood restored her youthful beauty. With the help of accomplices, Bathory killed a reputed 650 people, mostly young women, even children, and bathed in their blood. An investigation into the murders and disappearances led to Bathory's castle were bodies were found. She wasn't executed, but locked in a room without windows and mirrors. It was said that her obsession with her own vanity and not being able to see her own reflection drove her mad, and her madness ultimately killed her. It is said that this woman's bloody obsession was the one to spark the story of fictionalized vampires.
Twilight isn't the best example. It just stuck out like a sore thumb between Harry Potter and the Smurfs. 
both understandably contrary to Christian beliefs. 
