Croatia is a predominantly Christian country, with Islam being a minority faith. It is followed by 1.3% of the country's population according to the 2021 census. Islam was first introduced to Croatia by the Ottoman Empire during the Croatian–Ottoman Wars that lasted from the 15th to 16th century. During this period some parts of the Croatian Kingdom were occupied which resulted in some Croats converting to Islam, some after being taken prisoners of war, some through the devşirme system. Nonetheless, Austria strongly fought against the Turks during these few centuries which resulted in the fact that the westernmost border of the Ottoman Empire in Europe became entrenched on the Croatian soil. In 1519, Croatia was called the Antemurale Christianitatis by Pope Leo X in one letter, as well as Poland, Armenia or Albanians.

Islam is the majority religion in Azerbaijan, but the country is considered to be the most secular in the Muslim world. Various reports have estimated 97.3% or 99.2% of the population identifying as Muslim; with the majority being adherents of the Shia branch (55-65%), while a significant minority (35-45%) are Sunnis. Traditionally, the differences between these two branches of Islam have not been sharply defined in Azerbaijan.