Eastern Orthodoxy in Croatia in the context of "Macedonian Orthodox Church"

Church Slavonic is the conservative Slavic liturgical language used by the Eastern Orthodox Church in Belarus, Bulgaria, North Macedonia, Montenegro, Poland, Russia, Ukraine, Serbia, the Czech Republic and Slovakia, Slovenia and Croatia. The language appears also in the services of the Russian Orthodox Church Outside of Russia, the American Carpatho-Russian Orthodox Diocese, and occasionally in the services of the Orthodox Church in America.

In addition, Church Slavonic is used by some churches which consider themselves Orthodox but are not in communion with the Orthodox Church, such as the Montenegrin Orthodox Church and the Russian True Orthodox Church. The Russian Old Believers and the Co-Believers also use Church Slavonic.

Islam is the third-largest religion or subdivision and second-largest religion in Croatia after Roman Catholicism and Eastern Orthodoxy, which are Christian religions. The religion 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, Croats 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.

The Islamic Community of Croatia (Mešihat Islamske Zajednice u Hrvatskoj) is the main organization of Muslims in Croatia that is officially recognized by the state. The President of the Islamic Community is Aziz Effendi Hasanović. As of 2011, 62,977 Muslims live in Croatia. Most of them declare themselves as Bosniaks (31,479) while others declare themselves as: Croats (9,647), Albanians (9,594), Roma (5,039), Turks (343), Macedonians (217), Montenegrins (159), Ahmadies (16) and other (2,420).

The Ustaše (pronounced [ûstaʃe]), also known by anglicised versions Ustasha or Ustashe, was a Croatian fascist and ultranationalist organization active, as one organization, between 1929 and 1945, formally known as the Ustaša – Croatian Revolutionary Movement (Croatian: Ustaša – Hrvatski revolucionarni pokret). From its inception and before the Second World War, the organization engaged in a series of terrorist activities against the Kingdom of Yugoslavia, including collaborating with IMRO to assassinate King Alexander I of Yugoslavia in 1934. During World War II in Yugoslavia, the Ustaše went on to perpetrate the Holocaust and genocide against its Jewish, Serb and Roma populations, killing hundreds of thousands of Serbs, Jews, Roma, as well as Muslim and Croat political dissidents.

The ideology of the movement was a blend of fascism, Roman Catholicism and Croatian ultranationalism. The Ustaše supported the creation of a Greater Croatia that would span the Drina River and extend to the border of Belgrade. The movement advocated a racially "pure" Croatia and promoted genocide against Serbs—due to the Ustaše's anti-Serb sentiment—and Holocaust against Jews and Roma via Nazi racial theory, and persecution of anti-fascist or dissident Croats and Bosniaks. The Ustaše viewed the Bosniaks as "Muslim Croats", and as a result, Bosniaks were not persecuted on the basis of race. The Ustaše espoused Roman Catholicism and Islam as the religions of the Croats and condemned Orthodox Christianity, which was the main religion of the Serbs. Roman Catholicism was identified with Croatian nationalism, while Islam, which had a large following in Bosnia and Herzegovina, was praised by the Ustaše as the religion that "keeps true the blood of Croats."