Religious diversity has been a feature of Kurdistan for many centuries. Main religions that currently exist in Kurdistan are as follows: Sunni Islam, Shia Islam, Christianity, Zoroastrianism, Yarsanism, Yazidism, Alevism, and Judaism. Today, Sunni Islam is the most adhered religion in Kurdistan.
The majority of Kurds are Sunni Muslims. The exact proportion is uncertain but McDowall gives the percentage as 'approximately 75%', while Martin van Bruinessen estimates around two thirds or three quarters at least. Sunni Kurds follow the Shafi'i madhhab, which distinguishes them from Arab and Turkish neighbors who in general are Hanafi. This difference is identified by some Kurds as being essential to their ethnic identity and deliberately emphasized.
Historically, Kurds played an important role in Islamic intellectual development. Kurdistan was situated in a geographic location which enabled Kurds to equip Arabic, Persian and Turkish, all had been principal languages of Islamic civilization at different times. This condition had made Kurds playing mediators of different Islamic cultural centers. Kurdish ulama were especially significant at the high ranks of Ottoman Nizamiye Courts, Al-Azhar University in Cairo and the holy cities of Mecca and Medina in the Arabian Peninsula. After the secularization of Turkey, Turkish Kurdistan became the only remaining place where traditional Islamic institutions were preserved in the country, and many Turkish Muslim scholars went to Kurdistan in order to obtain the Islamic education.
Sunni Islam among Kurds is characterized by a strong overtone of mysticism and its scholars' affiliation with Sufi orders. In Kurdish society these constitute a hierarchical system, in which the leaders (sheikh) deploy their influence onto the localities through their deputies (khalifa), who mediate between sheikhs and common people. Today, Naqshbandiya and Qadiriyya are the most active tariqas. These tariqas had produced numbers of significant figures in the early history of Kurdish nationalist movement, including Mahmud Barzanji of Qadiriyyah, and Sheikh Said and Sheikh Ubeydullah of Naqshbandiyyah. Strong influences of sheikhs in the late 19th and the early 20th centuries were attributed to the Ottoman administrative reforms and the defense against the intrusion of Christian missionaries.
Modern political development among Sunni Muslim Kurds varies throughout the state to which they belong. In Turkey, Said Nursî exerted major influence. In the early days, Nursi contributed significantly to the formation of Kurdish nationalism. Later, Nursi broke with the nationalists and devoted himself to intellectual development. This became the basis of the Nur Movement which espoused Islamic Modernism, mysticism, compatibility with modern science and tolerance. The Nur movement garnered several million followings in the mid 20th century. The group fragmented substantially in the 1970s and 1980s, resulting in offshoots such as the Gülen movement. In Iraqi Kurdistan and Iran, although Muslims are pious, Islam didn't take a root as a strong political rallying force. Today, significant movements include Kurdistan Islamic Union led by Salaheddine Bahaaeddin and Kurdistan Islamic Group led by Ali Bapir.
There is a minority of Twelver Shi'i Muslims in southern parts of Kurdistan in Kermanshah, Khanaqin and the Ilam Province. The proportion of Kurds who ascribe to Twelverism is potentially up to 15%.
Yazidism is a monotheistic ethnic religion with roots in a western branch of an Iranic pre-Zoroastrian religion. It is based on the belief of one God who created the world and entrusted it into the care of seven Holy Beings. The leader of this heptad is Tawûsê Melek, who is symbolized with a peacock. Its adherents number from 700,000 to 1 million worldwide and are indigenous to the Kurdish regions of Iraq, Syria and Turkey, with some significant, more recent communities in Russia, Georgia and Armenia established by refugees fleeing Muslim persecution in Ottoman Empire. Yazidism shares with Kurdish Alevism and Yarsanism a lot of similarities that date back to pre-Islam.
Yarsanism (also known as Ahl-I-Haqq, Ahl-e-Hagh or Kakai) is also one of the religions that are associated with Kurdistan.
Although most of the sacred Yarsan texts are in the Gorani and all of the Yarsan holy places are located in Kurdistan, followers of this religion are also found in other regions. For example, while there are more than 300,000 Yarsani in Iraqi Kurdistan, there are more than 2 million Yarsani in Iran. However, the Yarsani lack political rights in both countries.
Zoroastrianism was one of the dominant religions in Kurdistan before the Islamic era. Currently, Zoroastrianism is an officially recognized religion in Iraqi Kurdistan and Iran and three Zoroastrian temples have opened in Iraqi Kurdistan after the official recognition of Zoroastrianism in the region in 2015. On 21 September 2016, the first official Zoroastrian fire temple of Iraqi Kurdistan opened in Sulaymaniyah. Attendees celebrated the occasion by lighting a ritual fire and beating the frame drum or 'daf'.
The Zoroastrian community in Iraqi Kurdistan has claimed that thousands of people have recently converted to Zoroastrianism in the region, however this has not been confirmed by independent sources and there are no official figures on the Zoroastrian population in the region. In 2020, it was reported there were 60 Zoroastrian families in Iraqi Kurdistan. At the same time, Reuters claimed many new predominantly Kurdish converts to Zoroastrianism in the Kurdistan Region are not officially registered as such, but some 15,000 members are counted by the Yasna association, which represents Zoroastrians.
Christianity is present in the Kurdistan Region of Iraq through the presence of several distinct communities, Kurdish Christians and non-Kurdish Chaldeans, Syriacs and Assyrians. The Chaldean, Syriac and Assyrian communities in the Kurdistan Region of Iraq live primarily in the Erbil and Dohuk Governorates.
There used to be a Jewish minority in most parts of Kurdistan, but most of them were forced to Israel in the mid-20th century. In the beginning of 20 century, the cities of Kermanshah, Orumieh, Piranshahr and Mahabad had the largest Jewish populations in Iranian Kurdistan.
According to recent reports, there were between 400 and 730 Jewish families living in the Kurdish region. However, Dr. Mordechai Zaken, an Israeli expert on Kurdish affairs, told the Jerusalem Post in November 2015 interview that the media reports on 430 Jewish families in Iraqi Kurdistan were false: "There were several dozen families that had some distant family connection to Judaism and most of them immigrated to Israel in the aftermath of the Gulf War...".
On October 18, 2015, the Kurdistan Regional Government named Sherzad Omar Mamsani, a Kurdish Jew, as the Jewish representative of the Ministry of Endowment and Religious Affairs. In 2017 Rabbi Daniel Edri, a Chief rabbi of rabbinical coury of Haifa in Israel, claimed he was appointed the chief Rabbi of Kurdistan by the Kurdish Region's Minister of Endowment and Religious Affairs. In 2018, Sherzad Memsani was removed from his position.
In the 21st century, Kurdish polities began adopting secularism as a political principle in the Middle East. This is not least due to the Kurdistan Communities Union movement and their radically secular Rojava model project in the Democratic Federation of Northern Syria. Kurdistan has been referred to as "the last safe haven for secularism" in a region rife with religious extremism. In 2012, the semi-autonomous Kurdistan Regional Government of Iraq (KRG) declared that public schools were to be religiously neutral and that all major religions of the world are taught on an equal basis. As of 2012, KRG and Rojava (Syrian Kurdistan), are the only administrations in the entire region that do not openly endorse a single religion in public schools.