The Yazidi religion is often misunderstood, as it does not fit neatly into Iraq’s sectarian mosaic. Most Yazidis are Kurdish speakers, and while the majority consider themselves ethnically Kurdish, Yazidis are religiously distinct from Iraq’s predominantly Sunni Kurdish population. Yazidism is an ancient faith, with a rich oral tradition that mixes with Islam some elements of Zoroastrianism, the ancient Persian religion, and Mithraism, a mystery religion originating in the Eastern Mediterranean. This combining of various belief systems, known religiously as syncretism, was part of what branded them as heretics among Muslims. While its exact origins are a matter of dispute, some scholars believe that Yazidism was formed when the Sufi leader Adi ibn Musafir settled in Kurdistan in the 12th century, and founded a community that mixed elements of Islam with local Zoroastrian beliefs.
Yazidis began to face accusations of devil worship from Muslims beginning in the late 16th and early 17th centuries. While the Yazidis believe in one god, a central figure in their faith is Tawusî Melek, an angel who defies God and serves as an intermediary between man and the divine. To Muslims, the Yazidi account of Tawusî Melek often sounds like the Quranic rendering of Shaytan—the devil—even though Tawusî Melek is a force for good in the Yazidi religion.
The Qurʾanic story of Shaytan/Satan (in which he’s called Iblis) says that he was cast out of Heaven for refusing God’s command that all creation should bow before Adam (Christian tradition says that Satan/Lucifer wouldn’t bow before God, but the circumstances of his fall aren’t explicitly stated in the Bible), because his pride would not allow him to prostrate himself before an inferior (mortal) being. Melek Tawus (the “Peacock Angel”) has a similar origin story in that he disobeys God’s (“God” for the Yazidis is a much more impersonal, deistic Creator figure than the personal interventionist God we see in the Abrahamic faiths) command to bow before the first man, but the Yazidis say that he does so out of love for God and a refusal to worship anything but God. Therefore he is rewarded by God with lordship over the Earth.
Adi b. Musafir, assuming that he was the founder of Yazidism, would not have been alone among Sufis in finding Iblis’s Qurʾanic story unsatisfying. Mansur al-Hallaj (d. 922), one of the first major mystical/Sufi figures in Islam, argued that Iblis refused to prostrate before Adam because he refused to violate God’s decree of tawhid (Oneness), that nobody and nothing should be worshiped apart from God, in the face even of God’s own command to do otherwise. This makes Shaytan a true monotheist, and later mystics took up this idea and made Iblis into almost a tragic figure, forced by his deep monotheistic principles to refuse a command from God and suffer the consequences.
Other mystics, like the famous Jalal al-Din Rumi (d. 1273), saw otherwise, and attributed Iblis’s disobedience to his own arrogance and his conceit that he, Iblis, having been created from fire, must be superior to Adam, who had been created from mere clay. He couldn’t understand that Adam’s clay had been crafted in God’s image and had the Divine Breath blown into him, which made Adam the superior creation. These musings over Iblis continued into modern times; the Indian mystic poet Muhammad Iqbal (d. 1938) suggested that Satan was evil but yearned to be defeated by the Perfect Man (insan al-kamil, another Sufi figure who is often Muhammad but could also be a great mystic and/or the Mahdi, or all of the above) so that he could repent and be forgiven by God. (Annemarie Schimmel’s Mystical Dimenstions of Islam goes into more detail about this stuff and has citations to other works on the topic).
For the Yazidis, whatever their roots, Melek Tawus’s story shares that one similarity with Iblis and then the two stories completely diverge, so this “devil worshiper” business is both unfair and, to the extent that it’s been used to justify attempts to exterminate their community, downright horrifying. Yazidi tradition holds that they’ve survived 72 attempted genocides, and I would think recent events could be counted as number 73.