One of the most iconic of images–the vampire cowering when confronted with a cross (makes one wonder how the creatures handle a graveyard?). Not quite what folklore tells, but containing a grain of truth. Religion and the idea of the dead drinking blood entwined long ago:
1. 
Vampire Burials
In recent years, archeologists found something of a goldmine when it came to publicizing their work–burials of what people evidently thought were vampires. Mercy Brown makes for an American example but Irish vampire graves as well as Italian and Polish ones have popped up. An Eastern European princess‘ grave was examined for evidence along those lines as well.
2.
Adam’s First Wife
Lilith may have begun as a Mesopotamian demon goddess, patroness and progenitor of vampires, but legend later made her the first bride of Adam. In this version, she mated with the fallen angel Asmodeus, giving birth to all the monsters that plague the Earth. In particular, with regards recent story-telling, she’s increasingly identified as the mother and queen of all vampires. Clearly this myth remains a living one, harkening to (among other things) misogyny.
3. 
Punishment
Like Medusa of old (turned into a death-dealing monster for the “crime” of being a rape victim), the idea of punishing women remains a meme in many faiths. Those who do wrong become monsters that increase the suffering of the world, especially if the wrong is done by women. Likewise in the last two centuries we’ve absorbed the notion so prominent in Dracula that vampires bring out the bestial side of females, especially in terms of sexuality.
4. 
Heresy
Religions also use the vampire myth to warn those who might harbor ideas outside what’s accepted. Medieval churches for example made a big point of ‘damning’ those who’d committed suicide, or who adhered to a variety of heresies. They were hardly alone. The Filipino Aswang, the Chinese Jiangshi and the Romanian Strigoi all violated social norms. This eventually translated into the idea that heresy was literally one of the ways experts insisted one could become a vampire!
5. 
Montague Summers
One such expert earned the title of a great eccentric in a nation of eccentrics–Reverend Montague Summers. Ordained as a deacon fairly early in life, the man donned clerical robes he was only technically allowed, eventually leaving the Anglican Church and more-or-less pretending to be a Catholic priest. A genuine medieval scholar, he accepted a medieval world view. His books insisted vampires were real (he saw them as malignant spirits rather than undead flesh and blood)! This attitude towards vampires remains with us today, at least among some religious types who react with such displeasure at the popularity of vampire fiction.
6.
Incubus
Our own age is one of scientific categories and specific definitions. In the past, this often was not the case, even among the most educated. So it was that the vampire and the incubus (a masculine demon who sexually ravages women in their sleep) weren’t necessarily considered different things. We of course see this today in the highly sexualized nature of our vampire stories. A vaguely vampiric detail (echoing the androgyny we see in the undead) is how the same demon as a succubus gains seed from a man, and then uses it to impregnate women as the incubus.
7. 
Wisdom of the Dead
Of course another eerie idea, one touched upon in other faiths rather than Christianity, is how vampires and the dead in general know things we do not. Hindu vampires (or blood drinking demons) were said to possess vast learning while Ulysses in Greek Myth went to the underworld to seek counsel. The dead needed blood in order to gain strength enough to speak, however, so first he had to feed them.
8. 
The Evil Place
Transylvania may summon up images of every movie monster we know (well, the classics anyway) but over the ages different religions warn us of other, more general locations to fear. In fact, much of the world seemed deeply mysterious and dangerous. The woods harbored who knows what? Graveyards were seen as literal homes of the dead. Likewise caves seemed like yawning pits into another realm where monsters, ghosts and demons might do all sorts of terrible things.
9. 
Rituals
We may think of religion as a matter of belief, but historically (even to this day) it often seems a matter of correct action. Vampires for example can be created when funerary rituals end up done wrong in some way. Likewise actually getting rid of an undead nearly always requires some precise formula. This was one reason the whole idea of not receiving last rites (or the local equivalent) could prove so terrifying. Likewise saints and their relics might prove essential in defending oneself.
10.
Appeasing the Undead
Halloween today is (mostly) a children’s holiday celebrating all thrills and chills. Its origins however lies in the (pagan–hence some fears on the subject) notion that one must give the monsters something to leave you alone. In Ancient Greece this ended up common. The Bacchae, worshipers of Dionysus (not at all like the Roman Wine God Bacchus) consisted of women working themselves into a state to kill wild animals with their bare hands. Likewise, the Furies–hideous creatures that embody vengeance–were given their own grove within the City of Athens. Perhaps the most obvious uses of this in terms of actual blood were Mesoamerica’s Aztecs.
11.
Natural Remedies
This takes a little mental adjustment. Christianity in the West has come to see faith and ritual as distinct from a fallen natural world. Yet most other religions in history look more strongly to the forces around us. Like some forms of Buddhism, Western Churches focus upon what is beyond this world. Yet in practice, most religions look upon nature itself as a manifestation if not some kind of gift from the divine. So garlic and vervain are seen as effective, along with sunlight (seen as sometimes uncomfortable for vampires). Besides, priests were relatively scarce, and travel hazardous. In terms of practical religion, most people looked elsewhere than the official hierarchy for aid against the bloodthirsty dead!
12. 
Sin
Although it takes different forms, Christianity most of all associates the undead with some kind of sin–very nearly all of the deadly seven in one way or another. In history Vlad the Impaler was not seen as a vampire, but others who committed evil deeds certainly were. More tellingly, vampires often seem to embody a sin–lust, gluttony, greed, vanity and the like. Disapproval by Church officials of belief in vampires explicitly mention superstition and/or apostasy. Thus every single aspect of vampires–from who becomes a vampire, and why, who is victimized by vampires, who hunts vampires, even who believes in the things–becomes laced with the Church’s notions of sin.
