The descent of the Holy Spirit upon the Apostles fifty days after Pascha, marking the full revelation of the Holy Trinity and the beginning of the Church's mission in the world. During Vespers, special kneeling prayers are offered and the church is adorned with greenery. This feast celebrates the completion of Christ's saving work and the outpouring of the Holy Spirit upon all believers. From this day forward, the Sundays of the year are numbered from Pentecost, signifying the continual life and growth of the Church in the grace of the Spirit.

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.

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 evening prayer service of the Orthodox Church, traditionally celebrated at sunset. Vespers includes psalms, hymns, scripture readings, and incense. On Saturday evenings, Great Vespers is often combined with the Sunday Divine Liturgy. The service marks the end of the liturgical day and prepares the faithful for rest and reflection.

The 20th-century Russian bishop who served Orthodox communities in China, Europe, and America. Celebrated on July 2nd, John (Maximovitch) was known for his ascetic life, care for orphans, and numerous miracles. He walked barefoot, rarely slept, and constantly prayed. He represents pastoral dedication and the universality of Orthodox faith across cultures.