Werewolves, a combination of man and wolf, are not vampires. Holy water and crucifixes have no effect on the creatures. However, it's long been believed that to kill a werewolf, you'll need a silver bullet, the type of bullet that is not as dense as a lead bullet.
According to Monstrous.com, the notion that silver kills a werewolf was born during the rise of the Catholic Church. "The claim that the Beast of Gévaudan, an 18th century wolf or wolf-like creature, was shot by a silver bullet appears to have been introduced by novelists retelling the story from 1935 onwards and not in earlier versions."
But the silver bullet is not a sure way to kill a werewolf. The way to kill a werewolf is to destroy its heart or its brain. Decapitation is a good way to do that.
I Love Horror/Paranormal Novellas Blog Hop August 2012