The Czech and Slovak Orthodox Church (Czechoslovak Orthodox Church up to 1993) traces its roots to the Church of the Czech Brethren of the 1920s. It was first headed by Matej Pavlik, ordained as bishop Gorazd by the Serb Orthodox Church under whose authority the Church operated.
Almost all of the members of the Czech and Slovak Orthodox Church were 20th century converts from Roman Catholicism or Eastern Rite Catholicism (Uniates). The faithful included Czechs, Moravians, Slovaks and back then Rusyns (Carpatho-Ukraine was a part of Czechoslovakia up to 1945) who felt disenfrachised by the Catholic priests. The conversions and the Church itself was an attempt to return to Slavic roots and to the teachings of the Saints Cyril and Methodius who first converted Moravia in 863.
The faithful of the then Czechoslovak Orthodox Church were Czechoslovak patriots as well as pan-Slavs and their ranks quickly grew from almost no Eastern Orthodox faithful to 145,000 by the 1931 census (of that some 120,000 Ruthenes in Carpatho-Ukraine).
In 1942, the head of the church, bishop Gorazd was arrested, tried and executed by the Nazis. His offence was harbouring the conspirators who had assassinated Reinhard Heydrich. This involvement caused harsh reprisals for Eastern Orthodox faithful in German-occupied Bohemia and Moravia. Some 256 Orthodox priests and prominent believers were either executed or deported to slave labour camps in the Third Reich.
Following the end of the war, in 1945, the Czechoslovak Orthodox Church held a memorial service for bishop Gorazd. Prominent citizens of Prague of all faiths paid their respects to the murdered cleric in the Orthodox cathedral of Sts Cyril and Methodius.