Islam is the majority religion in Azerbaijan, with various reports have estimated that 97.3% (CIA, 2020) or 99.2% (Pew Research Center, 2006) of the population identify as Muslim, with the majority (50–65%) being Shias and a significant minority (35–40%) being Sunnis. Traditionally, the differences between these two branches of Islam have not been sharply defined in Azerbaijan, as a major portion of the population are cultural Muslims. As such, the country is considered to be the most secular in the Muslim world.
Shia Muslims in the country typically adhere to the Ja'fari school of Shia Islam, while most Sunni Muslims follow the Hanafi 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.