The branch of christianity common in russia, bulgaria, greece, and romania is called?

The branch of Christianity common in Russia, Bulgaria, Greece, and Romania is called Eastern Orthodox. The official name is Orthodox Catholic Church, in which the name "Orthodoxy" literally means "right belief." The majority of Eastern Orthodox Christians live in Eastern Europe, Greece, and the Caucasus. The religious authority for Eastern Orthodoxy are scriptures as interpreted by the seven ecumenical councils of the Church (not the pope nor the Bible).