The origin of Werewolves can be traced to the Bible and Greek & Roman Mythology:
In the ancient myths of Greece and Rome men were transformed into wolves as punishment for bestial acts of murder or cannibalism. Thus moral degradation was seen as leading to physical degradation which served as a warning against bestial behavior.
The 1st recorded use of the word “Werewolf” was in the context of a familiar metaphor: Christians as Sheep protected by the Shepherds of the Church from the spiritual Wolves seeking to prey upon them. At this point the description of the Devil’s servants as Wolves seeking to devour the Faithful took on a literal as well as a spiritual meaning (perhaps inspired by classical myth). Human transformations into wolves and attacks by werewolves served as proof of the Devil’s power on Earth and validated Church authority.
Oddly, in the ballads and folk tales of the Middle Ages werewolves were often portrayed sympathetically as the victims of domestic plots. A righteous man cursed to be a werewolf reveals the secret to his wife. The wife betrays her husband depriving him of something he needs to reverse the transformation. With her husband trapped in the form of a wolf she takes on a lover. Eventually the wolf’s true nature is discovered, the object needed to restore the wolf to human form is found and the unfaithful wife is punished.
This sympathetic portrayal of Werewolves contrasts sharply with how “real” werewolves were treated. Accused werewolves were tortured and prosecuted as witches. All witches were believed to be able to transform themselves into animals using an ointment or belt given to them by the Devil. Werewolves were simply witches who had taken on the form of wolves in order to prey upon the lives and property of their neighbors. Werewolves would not come be seen as distinct from Witches until modern times.