The vampire is a unique and interesting breed of monster. It has historically been a very successful monster because it plays on some of our worst fears. Among these are temptation by the devil (as he is represented by the character of the vampire) and the question of what becomes of the body and soul upon death. The first fear pertains primarily to Christians, but I suppose non-religious types can also sympathize with the general fear of being tempted into any kind of danger. The second fear is perhaps deeper and more frightening because it is not necessarily one of morality, but actual physical laws. When we die, we accept the fact that our bodily functions cease and never again will return. Those who believe in a soul also believe in a specific destination for that soul. But then there is always that worry about what happens if something goes wrong. That is where the vampire comes in.
Of the six movies viewed, four contained definite religious undertones (and the other two are debatable). For example, in the Vampire Hunter D movies, Christ and Christianity are never mentioned, but still there is a cruciform object in nearly every scene. The sword that D uses to kill his vampire prey is shaped like a nearly proportionate cross and there are many cross shaped windows and steeples in the background. So while D appears to just use brute strength and cunning to defeat the vampires, we the audience actually get the feeling that his strength must come from a higher power. Bram Stoker's Dracula makes more obvious use of Christ and religious objects, with the characters actually using crosses and wafers to fend off the vampires. They try garlic and traditional cures at first, perhaps representing a willingness to stick to modern man's devices, but when those fail they must inevitably turn back to the church. The movie with the greatest religious presence was certainly John Carpenter's Vampires. Here we had a team of men (with their trusty priest companion) clearing out vampire nests, but soon most of the team is killed leaving the leader James Crow (who, not so coincidentally, shares initials with Jesus Christ) to finish off the vampire Valek. Another interesting detail is that the team stays at the Sun-God Motel. These two elements have historically been the only two effective against vampires and here they are linked (and logically too because who created the sun after all?) It is also no surprise to find that Valek (like Dracula) was created because he turned his back on God. Clearly here, then, we see the message to cling to the church at all times.
Even more basic to all of the movies, though, is the game that they play with the notion of death. In real life when someone gets viciously attacked by a wild animal or beast, we expect them to bleed a lot and die. We will mourn their loss, but come to terms with it and eventually move on. This process gets complicated, though, in vampire movies. The biggest problem is that the attack does not kill the victim, nor does it allow them a normal recovery. The victim is left in a strange in-between state where they are neither alive nor dead, but simply "undead." This notion is similar to that of ghosts (souls who continue to haunt the earth from the grave) only it is more threatening because the vampires are not just passive wanderers, but active seekers of victims. When a friend or relative gets bitten, the survivors cannot accept the loss because they are unsure of the person's fate. The horror of the vampire story is the fact that the sacred security of the grave is taken away.
The Blade movies make good use of this death game as a means of connecting the first movie to the sequel. In the end of the first, Whistler supposedly shoots himself and yet somehow we find him sustained by a pool of blood in the second. Also in Bram Stoker's Dracula we find that mere death is never the end. Lucy's final hours are filled with grief and then when she finally passes away she is not even granted peace. Once again there is this notion that there is something beyond the grave and so we must too venture into that unknown place.
In recent decades there has been an explosion of vampire movies and this must be attributed to the fact that the recurring themes of vampire stories are very relevant in our modern times. The vampire teaches us to cling to the cross at a time when congregations are shrinking and more and more people are falling away from the church. Advancing medical knowledge now allows doctors to revive people who we would have traditionally seen as dead. New technology like cryogenics also adds new questions about how exactly we define death.