Yazidism holds that there is one God, who created the world and entrusted its care to seven holy beings. The chief of them is Tawusi Melek, the Peacock Angel, God's regent over the world, and it is to him that Yazidi devotion is chiefly addressed. He is not a rival to God and not an independent power; he is the form in which the divine will meets creation.
Outsiders have persistently identified him with the Devil. The identification rests on a story that Yazidism shares with Islamic and Jewish tradition and reads in the opposite sense. God commands the angels to bow before the newly created Adam, and one refuses. In the Quranic telling the refuser is Iblis and the refusal is damnable pride, the origin of Satan. In the Yazidi telling the refusal is obedience, because the angel had been commanded earlier and more fundamentally to bow to no one but God, and he is vindicated and exalted for holding to it. The same narrative, the same refusal, opposite verdicts.
The Yazidi position is not that they worship a misunderstood devil. It is that there is no devil. Evil in Yazidi teaching is not a person and holds no kingdom of its own; it originates in the human heart. There is no adversary figure for Tawusi Melek to be. Yazidis do not utter the Arabic name of Satan and avoid words that merely resemble it in sound, an avoidance strict enough to have shaped everyday vocabulary, which outsiders have sometimes taken, backwards, as evidence of reverence for the being whose name is not said.
The correction is not a matter of courtesy. Devil-worshipper has been the standing charge in the persecutions Yazidis count as firmans, and it supplied the legal pretext for the worst of them. Islamic State propaganda in 2014 argued explicitly that Yazidis were devil-worshippers rather than People of the Book, and therefore could be enslaved rather than taxed. The libel and the atrocity are directly connected.