Most Kurds are Sunni Muslims, and among them are many who practice Sufism and other mystical sects. Smaller numbers of Kurds are Shiʿah or Alawites. A minority of Kurds are not Muslim, including a growing number of agnostics and atheists. Members of the Yazīdī religious minority—whose religion includes elements of ancient Iranian religions, as well as elements of Judaism, Nestorian Christianity, and Islam—are ethnically Kurdish.
The Kurds are often discussed as one of the three main population groups in Iraq, along with the Sunni and Shiʿah. This terminology is used to contrast them with their Sunni Arab and Shiʿi Arab neighbors, rather than to imply that Kurds are not Muslim.