A group whose origins predate Abraham and has absorbed waves of persecution still survives in Iraq. Ed O'Loughlin reports from Erbil.
Please allow me to introduce the Yezidis, a Kurdish tribe of little wealth and eccentric taste. Scholars believe that the Yezidi community's strange and ancient religion is one of the last surviving offshoots of a faith even older then Judaism or Zoroastrianism, which it heavily influenced.
Known as "the cult of the angels", this early Indo-European faith held that there was only one God but that he created seven angels to serve him. Chief among these, for the Yezidis, is the angel who disobeyed his maker. The fallen angel, in other words.
"They are devil worshippers," confides Yussuf Saleem, a Muslim restaurateur in Erbil. "It's well known that they pray to Satan. Apart from that, they seem to be nice people."
Allegations of devil-worship have dogged the Yezidis for at least 1000 years. While the great majority of their fellow Kurds became Sunni Muslims centuries ago, the Yezidis have preserved the essence of their ancient faith through wave after wave of religious persecution.
"Yezidism is a valid religion and at the time when people were being forced to become Muslims, because we were near the mountains we were able to keep it," says Hashim Hassan, a resident of the small Yezidi capital, Shekhen, half an hour's drive north of Mosul, stands where the last ripple of the Zagros mountains meet the flat Mesopotamian plain.
Many Yezidis were swept up in Saddam Hussein's crackdown on the Kurds in the 1980s.
Apart from being subject to the general persecutions imposed on Kurds and Shia Arabs by Iraq's Sunni Arab minority elite, the Yezidis were often singled out for petty harassment.
"They saw us as beneath them," says Hashim Hassan.
The Yezidis' hereditary ruler, Emir Tasseen Sayid Ali Bak, bemoans the loss of more than 30,000 hectares of the tribe's best land in recent years, to Sunni Arabs transplanted from the south. "There were more than 60 villages that they took over," he says.
The Emir says that most of the Arabs fled soon after the beginning of the US-led invasion, many taking refuge in nearby Mosul. He hopes Shekhen will be incorporated into the nearby Kurdish autonomous zone.
The emir is still recognised as the worldly leader of Yezidis living not only in their Iraqi heartland but also in Turkey, Syria, Georgia, Azerbaijan and Russia. There are several thousand Yezidis in Germany, and a few in Australia.
No one knows quite how many Yezidis there are in the world. The Emir reckons there could be 1.4 million, half in Iraq. Some Kurdish scholars have put the total as low as 200,000. Despite strict rules against marrying outside the faith, continuing emigration and religious persecution mean numbers probably are still in decline.
The Yezidis reject the widespread Iraqi belief that Yezidism lacks organisation, theology and scripture - that it is not a proper religion at all. In fact, Yezidism has two major books of revelation, written 1000 years ago and attributed to Sheik Adi Musafir and his son, the founders of this branch of the Cult of Angels.
The community maintains a strict caste system and three orders of priesthood, headed by the spiritual leader known as the Bab el Sheik.
The present Bab el Sheik, Kurto Haji Ismail, lives in Shekhen in an old house, the front doors of which are decorated with peacocks, symbol of Melek Taus, "the Peacock Angel".
"All the other religions - the Jews, the Muslims and the Christians - at the beginning they were all one religion," he says. "They are the sons of Abraham. We are older than Abraham. We came before."
The main reason for the persecution of Yezidism, he says, is confusion between its account of the creation and the very similar - but crucially different - Judaeo-Christian-Islamic one. "God created the seven angels and he told them that that they must worship no one else but him," the Bab el Sheik explains.
"After that, to test the angels, God told the angels that they should pray to Adam, and all the angels obeyed the order but one.
"The Peacock Angel refused. He said to God, 'You told us not to pray to anyone but you.' And because of that he passed the test. God forgave him and he became the greatest of the Angels.
"People say that we don't believe in God, that we believe in evil. But it is not true to say that the Peacock Angel broke the will of God. We say that the Peacock Angel passed the test of God, and is the good angel."
It is difficult, though, to blame Christians and Muslims for confusing the proud peacock with Lucifer, whose sin was pride. And Yezidism has long been notorious for syncretism, a fancy way of saying that it picks up bits of other religions as it goes along.
The founder of Yezidism, Sheik Adi, was himself a member of a wandering order of Muslim Sufi mystics. His burial place at Lalish, a lush and very beautiful valley north of Shekhen, is the faith's main temple, part of a complex of shrines that are a place of pilgrimage for Yezidis.
Here rise two sacred springs - the White Fountain and Zim Zim (the same name as a stream in Mecca). A series of channels and basins divert the swift-running waters through two giant stone fonts - like Christians, the Yezidis practise baptism - and then under the main temple, its door guarded by a black stone serpent. The streams reappear here and there amid the temple's labyrinth of dark passages, pillars, courtyards and sanctums. The sound of running water can always be heard.