Orthodox Christians across the world are celebrating Christmas.At Christ the Saviour Cathedral in Moscow, Russian President Dmitry Medvedev and his wife were among the worshippers. The midnight service, attended by more than 3,000 people, was led by Metropolitan Kirill, the interim head of the Russian Orthodox Church. In Serbia, branches have been burned on bonfires as part of the Christmas tradition. The religious holiday is observed on January 7 by churches that follow the Julian calendar. Revered as the birthplace of Jesus, Bethlehem went ahead with its midnight mass, at the Church of the Nativity. The service, held in the presence of senior Palestinian figures, comes as many thoughts in the West Bank are with the people of Gaza. Other than strictly religious events, authorities in Bethlehem have cancelled all Christmas celebrations.