Islam is the majority religion in Azerbaijan, but the country is considered to be the most secular in the Muslim world. Estimates include 97.3% (World Factbook of CIA, 2020) and 99.2% (Pew Research Center, 2006) of the population identifying as Muslim. Of these, a majority belong to the Shia branch (55-65%), while a significant minority (35-45%) are Sunni. Traditionally, the differences between these two branches of Islam have not been sharply defined in Azerbaijan. And also, Azerbaijan's strong relationship with Turkiye increases its Sunni population, while Shia Islam is in decrease.
Most Shia Muslims in the country follow the Ja'fari school of Shia Islam, while Sunni Muslims typically adhere to either the Hanafi or Shafi'i school. Due to many decades of Soviet atheist policy, religious affiliation in Azerbaijan is often nominal and Muslim identity tends to be based more on culture and ethnicity than on religion. Shia Islam is prevalent in the western, central, and southern regions of the country. Traditionally, villages around Baku and the Lankaran region are considered Shia strongholds. In contrast, Sunni Islam is dominant in the northern regions.
The rest of the population adheres to other faiths or are non-religious, although they are not officially represented. Other traditional religions or beliefs that are followed by many in the country are the Armenian Apostolic Church (in Nagorno-Karabakh), the Russian Orthodox Church, and various other Christian denominations.
Like all other post-Soviet states formerly ruled by the Soviet Union, Azerbaijan is a secular state; article 48 of its Constitution ensures the freedom of religion. A 1996 law states that foreigners have freedom of conscience, but are denied the right to "carry out religious propaganda", i.e., to preach, under the threat of fines or deportation. According to paragraphs 1-3 of Article 18 of the Constitution the religion acts separately from the government, each religion is equal before the law and the propaganda of religions, abating human personality and contradicting to the principles of humanism is prohibited.
Islam
The role of Islam in politics and in everyday life in Azerbaijan remains relatively small. Surveys in the late Soviet and early post-Soviet era generally found that although the vast majority of Azerbaijanis identify themselves as Muslims, less than a quarter of those who considered themselves Muslims "had even a basic understanding of the pillars of Islam". For many Azerbaijanis, association with Islam tended toward a more ethnic/nationalistic identity than a purely religious one. A 1998 poll estimated the proportion of ardent believers in Azerbaijan at only 20 percent.
In the post-soviet period, although the majority of Azerbaijan's population still nominally identifies with Islam, studies show that the Azerbaijani society has remained relatively secular in the years following the collapse of the Soviet Union. While the estimates identify 93–99% of Azerbaijan's population as adherents of Islam, the importance of religion on everyday life remains low. According to government estimates, Muslim population is approximately 55-65% Shia and 35-45% Sunni, however, officially the differences have not been sharply emphasized. Azeri Shi'a relations with Iran, its neighbour and the dominant Shi'i power, are not close, at least as of the mid 1990s. The head of Azeri Shi'ite clergy, Shiekh Haji Humat Pashazada, adheres to the quietist school of Abu al-Qasim al-Khu'i and was a pupil of Iranian cleric Mohammad Kazem Shariatmadari. (both clerics were strong opponents of Khomeinist doctrines and the repressive policies of the Iranian government).
The Azerbaijani government maintains a secular position. Article 7 of the Azerbaijani constitution officially declares Azerbaijan a secular state. Article 18 declares the separation of religion and state, the equality of all religions before the law, and also declares the secular character of the state educational system. In December 2010, Azerbaijan's Education Ministry, announced the ban on hijab, whereby students are forbidden from wearing hijabs in schools and universities. In April 2021, an additional set of proposals were submitted to the Azerbaijani parliament introducing additional, intensely secular amendments to Azerbaijan’s Religion Law and Administrative Code.