This feast is celebrated 28 days after Easter Sunday and is dedicated to the Apparition of the Holy Cross in Jerusalem. At noon on May 19, 351AD, a bright, luminous cross appeared over the skies of Jerusalem, centred over an area spanning from the Mount of Olives (where Christ was betrayed and arrested) to Golgotha (where Christ was crucified). Bishop Cyril (later St. Cyril of Jerusalem) subsequently wrote a letter to Emperor Constantine of Byzantium wherein he describes the miraculous and beautiful scene. St. Cyril tells Constantine that the apparition is a true testimony of the Orthodox faith of Christianity. Further, St Cyril exhorts the Emperor that the appearance is a sign for him to remain steadfast in his faith and to stop defending the heretical movement of Arianism (Arianism holds that the Son is distinct from the Father and therefore subordinate to Him) and its lawmakers.
The Armenian translation of the Bishop’s letter has been preserved by the Church and is read each year on the Feast of the Apparition of the Holy Cross.