High Quality Content by WIKIPEDIA articles! The Orthodox Church, officially called the Orthodox Catholic Church and commonly referred to as the Eastern Orthodox Church, is the second largest Christian denomination in the world, with an estimated 300 million adherents mainly in the countries of Belarus, Bulgaria, Cyprus, Georgia, Greece, Macedonia, Moldova, Montenegro, Romania, Russia, Serbia, and Ukraine, all of which are majority Eastern Orthodox. It considers itself to be the One, Holy, Catholic and Apostolic Church established by Jesus Christ and his Apostles almost 2,000 years ago.