Divine Liturgy of St. John Chrysostom
As the action initiating the Incarnation of Christ, Annunciation has such an important place in Orthodox Christian theology that the festal Divine Liturgy of St. John Chrysostom is always celebrated on the feast, even if it falls on Great and Holy Friday, the day when the crucifixion of Jesus is remembered. Indeed, the Divine Liturgy is celebrated on Great and Holy Friday only when the latter coincides with the feast of the Annunciation. If the Annunciation falls on Pascha (Easter Sunday) itself, a coincidence which is called "Kyriopascha", then it is celebrated jointly with the Resurrection, which is the focus of Easter. Due to these and similar rules, the rubrics surrounding the celebration of the feast are the most complex of all in Orthodox Christian liturgics.