The
Greek Orthodox Church of Jerusalem (,
Patriarcheîon Hierosolýmōn;
Kanisatt Ar-rum al-Urtudoks fi al-Quds, literally
"Church of the Rûm Orthodox in Jerusalem"), also known as the
Orthodox Patriarchate of Jerusalem, is an
autocephalous Orthodox Church within the wider communion of
Orthodox Christianity. Headed by the
Patriarch of Jerusalem, it is regarded by
Orthodox Christians as the mother church of all of
Christendom.
Christians believe that it was in
Jerusalem that the Church was established on the day of
Pentecost with the descent of the Holy Spirit on the disciples of
Jesus Christ and that the
Gospel of Christ spread from Jerusalem. The Church celebrates its liturgy in the
Byzantine Rite, whose original language is
Koine Greek, and follows its own calendar of feasts, preserving the Julian calendar (that is thirteen days behind the Western (Gregorian) calendar). It is also often called "Σιωνίτις Εκκλησία" (, i.e. the "Church of
Zion").