The celebration of Christ's ascension into heaven forty days after His Resurrection, witnessed by the Apostles. This moveable feast always falls on a Thursday and marks Christ's return to the Father and His promise to send the Holy Spirit. The feast emphasizes both Christ's divine nature and His continued presence with the Church.

The first Christian Emperor Constantine the Great and his mother, St. Helen, who found the True Cross. Celebrated on May 21st, this feast honors Constantine's legalization of Christianity and Helen's pilgrimage to the Holy Land. Their work established Christianity's place in the Byzantine Empire and preserved many holy sites.

The central worship service of the Orthodox Church, celebrating the Eucharist (Holy Communion). Usually celebrated on Sundays and feast days, the Divine Liturgy consists of the Liturgy of the Word (scripture readings) and Liturgy of the Faithful (Eucharistic prayer and communion). The most common forms are the Liturgies of St. John Chrysostom and St. Basil the Great.