Johannes Nider’s Formicarius was a demonological treatise written during the Council of Basel in Switzerland. Nider’s treatise detailed the features that were commonly thought to be a part of the witches’ sabbat, including cannibalistic infanticide as an initiation ritual:
“When Peter had questioned one of the captured witches how they ate babies, she said: ‘This is how. With unbaptized babies… we kill them in our ceremonies, either in their cradles or by the sides of their parents, who afterwards are thought to have suffocated or to have died in some other way. We then quietly steal them from their graves and cook them in a cauldron until their bones can be separated from the boiled meat and broth… From the more liquid fluid, we fill up a flask or a bottle made out of skins, and he who drinks from this, with the addition of a few ceremonies, immediately becomes an accomplice and a master of our sect.”
Nider’s treatise also details the renunciation of Christianity as an initiation ritual:
“First, on the Lord’s day, before the holy water is consecrated, the future disciple must go with his masters into the church, and there in their presence must renounce Christ and his faith, baptism, and the Church universal.”
Johannes Nider, “An Early Description of the Witches’ Sabbath, 1435” in The Witchcraft Sourcebook, ed. Brian P. Levack (New York: Routledge, 2004), 52-55.