the thing i like about the yazidi religion is its syncretic nature. it has captured bits and pieces of other religions and made a beautiful new story of its own.
"The Yazidi believe in God as creator of the world, which he has placed under the care of seven "holy beings" or angels, the "chief" (archangel) of whom is Melek Taus, the "Peacock Angel." In Zoroastrian-like tradition, the Peacock Angel embodied humanity's potential for both good (light) and bad (dark) acts, and due to pride temporarily fell from God's favor, before his remorseful tears extinguished the fires of his hellish prison and he reconciled with God."
wikipedia
seems to throw some light on how other religions with equally diverse-seeming mythologies may have formed.