Religion in Iraq dates back to Ancient Mesopotamia, particularly Sumer, Akkad, Assyria, and Babylonia between c. 3500 BC and 400 AD. Iraqi society consists of a multi-ethnic and multi-religious population, with Islam having been the dominant faith for centuries.
The religious practices of Iraq are shaped by its rich civilizational history, with Ancient Mesopotamian, Persian, Arab and Judeo-Christian influences. Several religions such as Christianity, Mandaeism, Islam, Yazidism, Zoroastrianism and Yarsanism have been practiced in Iraq for centuries.
Iraq's Muslims are split between the Shia and Sunni sects. Approximately 95% to 98% of the population are Muslims, with Shia Muslims constituting around 55% and Sunnis around 40%. Despite being an Arab country within the Arab world, its geopolitical history with Iran has meant that Iraq is majority Shia.
History
The religious development of Mesopotamia and Mesopotamian culture in general, especially in the south, was not particularly influenced by the movements of the various peoples into and throughout the area. Rather, Mesopotamian religion was a consistent and coherent tradition which adapted to the internal needs of its adherents over millennia of development.
There was increasing syncretism between the Sumerian and Akkadian cultures and deities, with the Akkadians typically preferring to worship fewer deities but elevating them to greater positions of power. Circa 2335 BC, Sargon of Akkad conquered all of Mesopotamia, uniting its inhabitants into the world's first empire and spreading its domination into ancient Iran, the Levant, Anatolia, Canaan and the Arabian Peninsula. The Akkadian Empire endured for two centuries before collapsing due to economic decline, internal strife and attacks from the north east by the Gutian people.
Modern era
The "Global Index of Religiosity and Atheism" listed Iraq as one of six countries as having the lowest rate of atheism in 2012. After six years, with religious figures coming to power, the situation changed fast as the tide of religiosity receded. According to Iraqi thinker Izzat Shahbandar, this came after their ruling political class came to power, and their role in sectarianism and state corruption, and by regularly occupying television slots to spread their agendas. The increasing prevalence of atheism and agnosticism signals a tidal public opinion change.
Iraq has Islam as the official religion of the state, according to Article 2 of the Constitution, Article 14 of which states that all Iraqis are equal before the law without discrimination. Article 43 of the Constitution gave freedom to followers of every sect to practice their religious rituals, and emphasized the Husseini rituals, and that the state guarantees freedom of worship and the protection of its places. The population, according to the latest census prepared by the Central Agency for Public Mobilization and Statistics for the year 2017, is 37 million, 139 thousand, and 519 people, with a growth rate of 2.61%, with a male-to-female ratio at birth of 103.9%.
In 2005, the population was 27,962,968, according to the Central Bureau of Statistics. The population, according to the Ministry of Planning and Development Cooperation for 2015, reached 36 million people, an increase of 5 million from 2009, when the number reached 31.6 million people. Iraq conducted its first nationwide population census in decades in 2024. Final results announced in November 2025 recorded a population of 46,118,793. The census did not distinguish between Sunni and Shia Muslims and did not collect ethnicity data, limiting its usefulness for estimating the populations of some ethnoreligious minorities.
Islam
Iraq's Muslims follow two distinct traditions, Shia and Sunni Islam. According to the CIA World Factbook, Iraq is approximately 95% to 98% Muslim, with approximately 55% Shia and 40% Sunni. According to a 2011 survey by Pew Research, 51% of the Muslims identify as Shia and 42% as Sunni. Iraq is home to many religious sites important for both Shia and Sunni.
Baghdad was a hub of Islamic learning and scholarship for centuries and served as the capital of the Abbasids. The city of Karbala has substantial prominence in Shia Islam as a result of the Battle of Karbala, which was fought on the site of the modern city on 10 October 680. Similarly, Najaf is renowned as the site of the tomb of Alī ibn Abī Tālib (also known as "Imām Alī"). The Shia consider him to be the righteous caliph and first imām. The city is now a great center of pilgrimage from throughout the Shia Islamic world even though his grave is debatable and it is estimated that only Mecca and Medina receive more Muslim pilgrims.
The city of Kufa was home to the famed Sunni scholar Abu Hanifah, whose school of thought is followed by a sizable number of Sunnis across the globe. Likewise, Samarra is home to the al-Askari Mosque, containing the mausoleums of the Ali al-Hadi and Hasan al-Askari, the tenth and eleventh Shia Imams, respectively, as well as the shrine of Muhammad al-Mahdi, known as the "Hidden Imam", who is the twelfth and final Imam of the Shia of the Ja'farī Madhhab. This has made it an important pilgrimage centre for Ja'farī Shia. In addition, some female relatives of the Islamic prophet Muhammad are buried in Samarra, making the city one of the most significant sites of worship for Shia and a venerated location for Sunnis.
Smaller sects of Islam exist in the country, such as the small Shia Shaykhist community concentrated in Basra and Karbala.
Arabs Iraqi Arabs are a mix between Shia and Sunni. The Arab Sunni live mainly in the area of the so-called Sunni Triangle, but there are other communities in other parts of the country, whereas the Arab Shia live mainly in Southeast Iraq. The capital Baghdad is mixed of Arab Sunni and Arab Shia as well as other religions.
Kurds
Iraqi Kurds are around 70% Sunni, with a Shia Feyli minority of 30%. Most Kurds are located in the northern areas of the country. Most Iraqi Kurdish Muslims follow the Shafi school of Islamic law, while others are members of either the Qadiri or the Naqshbandi Sufi tariqah.
Turkmen About 75% of Iraqi Turkmen are Sunni, and about 25% practice Shia Islam. Collectively, most Iraqi Turkmen are secular, having internalized the secularist interpretation of state–religion affairs practiced in the Republic of Turkey. The religious and tribal factors and tensions inherent in Iraq's political culture do not significantly affect the Iraqi Turkmen Sunnis and Shias..
Christianity
Christianity was brought to Iraq in 40's AD/CE by Thomas the Apostle, Thaddaeus of Edessa and his pupils Aggagi and Mari. Thomas and Thaddeus belonged to the twelve Apostles. Iraq's indigenous Assyrian people represent roughly 3% of the population (earlier CIA Factbook), mostly living in Northern Iraq, concentrated in the Ninewa and Dahuk governorates.
Iraq's Christian population declined substantially during the late 20th and early 21st centuries, particularly following the 2003 Iraq War and subsequent violence and displacement. According to Christian leaders and other sources cited by the U.S. Department of State in 2023, fewer than 150,000 Christians remained in Iraq, compared with an estimated 1.5 million before 2003. Approximately 67% were Chaldean Catholics and nearly 20% belonged to the Assyrian Church of the East; Armenian community leaders estimated approximately 12,000 Armenian Christians remained in the country.
Assyrians in Iraq are divided into five church bodies: Chaldean Catholic Church Assyrian Church of the East (and Ancient Church of the East) Syriac Orthodox Church "Eastern Orthodox" group (Archdiocese of Baghdad, under jurisdiction of the Eastern Orthodox Patriarchate of Antioch and All the East) "Eastern Evangelical" for the alliance Protestant.
Assyrians constitute 0.5% of the population of Iraq. They are a Semitic people who settled in the northern part of Iraq since the third millennium BC. Assyrians speak the modern Assyrian language, also known as Syriac in church literature, due to its spread by the Church of the East, which was known as Syriac.
Yazidism
The Yazidis are an ethnoreligious minority concentrated primarily in Nineveh Governorate and the Kurdistan Region of Iraq. Yazidi community leaders estimated the Iraqi population at approximately 400,000 to 500,000 in 2023. The community continues to experience the effects of the Yazidi genocide perpetrated by the Islamic State beginning in 2014. Large numbers of Yazidis have remained internally displaced, and reconstruction and return to Sinjar have proceeded slowly.
Zoroastrianism Zoroastrianism was one of the dominant religions in Northern Mesopotamia before the Islamic era. Currently, Zoroastrianism is an officially recognized religion in Iraqi Kurdistan and Iran.
Zoroastrianism has become the fastest growing religion with Kurds, especially in Kurdish-controlled Northern Iraq. Because of the religion's strong ties to Kurdish culture, there has been a recent rebirth of Zoroastrianism in the region, and as of August 2015 the Kurdistan Regional Government (KRG) officially recognized Zoroastrianism as a religion within Kurdish Iraq. Arguably the world's oldest monotheistic religion, Zoroastrianism (Zardashti in Kurdish) has almost disappeared in the last century until recent years. According to Yasna, an association that promotes Zoroastrianism in Kurdistan, since 2014 about 15,000 people have registered with the organization, most of them Kurds converting from Islam. People in Iraqi Kurdistan have converted to Zoroastrianism from a Muslim background since 2015, with the first new Zoroastrian temples being built and opened in 2016.
Many Kurdish people converted from Islam to Zoroastrianism, especially after ISIL attacked Iraqi Kurdistan. The surge in Kurdish Muslims converting to Zoroastrianism, the faith of their ancestors is largely attributed to disillusionment with Islam after the years of violence and barbarism perpetrated by the ISIS terrorist group. A Kurdish Islamic cleric claimed that Zoroastrianism was forced on Kurds by "fire-worshipping Persians", where as Islam liberated them, and he called on Kurdish Muslims to kill Zoroastrian converts if they do not convert back to Islam in 3 days.
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. There are no accurate numbers on the population of Zoroastrians in Iraq because they are listed as "Muslims" on their government-issued documents. According to the KRG MERA, there are approximately 80,000 to 100,000 Zoroastrians in the Iraqi Kurdistan Region.
Mandaeism
The Mandaeans are an ethnoreligious community historically concentrated in southern Iraq, particularly in areas along the Tigris and Euphrates river systems. Flowing water has particular religious importance because Mandaean baptismal rituals are traditionally performed in rivers. Estimates of the community's current size vary; according to Mandaean community leaders cited by the U.S. Department of State in 2023, approximately 10,000 to 15,000 Mandaeans remained in Iraq, mainly in the south, with between 450 and 1,000 living in Baghdad and the Kurdistan Region.
Mandaeism is a religion whose followers believe that it is one of the oldest known religions in human history, and that their first prophet and teacher was Adam, then his son Seth, Sam bin Noah, and John bin Zachariah (John the Baptist), peace be upon them. The Mandaeans say that they follow John.