Well, not exactly. Medieval theology, as many of us learned in seminary, continued the ancient Greek practice of dividing the universe into four substances: air, fire, water, and earth. Each was associated with a humor in the human body: blood, yellow bile, phlegm, and black bile. Keeping these humors in balance led to healthy bodies. Gardenour Walter, who teaches history in a Pharmacology school, shows how monsters were often viewed against this paradigm. As she notes, this Weltanschauung was not friendly to women. Seeing man as the perfect, rational being, women were considered less rational and more controled by their base urges, leading to the concept of witches. Witches were also associated with demons at a later time, and there is a considerable discussion of that transition.
Vampires were often associated with black bile. Although there are vampiric beliefs going back to very ancient times, Gardenour Walter shows how the modern vampire indeed derives from medieval theology as eastern ideas met western. Unfortunately, in unenlightened times, the concepts were anti-semitically applied, with unwonted liberality. Werewolves were generally dismissed as illusions wrought by demons, although, there always remained an ambiguity. I have to admit not having known that even Augustine discussed werewolves in The City of God, which, it comes to mind, would make an excellent horror movie. The book brings each of these medieval monsters up to the silver screen and considers how their theological pedigree plays out in modern times. This is a book I would have enjoyed as a college student, but maybe, secretly, enjoy even more now as an adult.