Malleus Maleficarum

The Malleus Maleficarum, or Hammer of the Witches, was a theological treatise written by the former-Catholic clergyman Heinrich Kramer. The treatise is surprisingly boring, consisting mostly of medieval-age theological arguments for the existence of demons, the practice of witchcraft, the supposed ways demons and witches operate, and the means by which they are to be countered.

Of course, what makes the Hammer of the Witches so detestable from an ethical standpoint is how it authorizes the eradication of witchcraft practices from Christian society! Kramer fully endorsed the practice of witch finding and his seminal tome was instrumental in the preceding centuries as the go-to handbook for those involved in some of the worst witch hunts known to history.

Links
https://en.wikipedia.org/wiki/Malleus_Maleficarum