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 beginning of the Orthodox liturgical year on September 1st. Also called the Indiction, this feast marks the start of the annual cycle of feasts and fasts. Many Orthodox churches hold special services with prayers for the new year, blessing of schools, and remembrance of God's creation. It emphasizes new beginnings and spiritual renewal.

A devotional service of praise consisting of hymns sung while standing ("akathist" means "not sitting"). The most famous is the Akathist to the Theotokos, traditionally sung during the fifth Friday of Great Lent. Akathists can honor Christ, the Theotokos, or various saints. These services are deeply moving expressions of Orthodox hymnography and devotion.

The sacrament of initiation into the Orthodox Church, through which a person is united with Christ in His death and resurrection. The baptismal candidate is immersed three times in water in the name of the Father, Son, and Holy Spirit, dying to sin and rising to new life in Christ. Baptism cleanses from original sin, grants adoption as God's child, and makes the person a member of the Body of Christ. In Orthodox practice, baptism is immediately followed by chrismation and first communion.

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 celebration of Christ's birth in Bethlehem. The feast is preceded by a 40-day Nativity Fast and celebrated with the Divine Liturgy, special hymns like the Troparion of the Nativity, and the blessing of homes.

The celebration of the birth of the Virgin Mary to Saints Joachim and Anna. This feast, observed on September 8th, marks the beginning of our salvation history, as Mary's birth prepared the way for the Incarnation. The Church honors Mary as the bridge between the Old and New Testaments.

The 20th-century Russian monk of Mount Athos known for his mystical experiences and spiritual writings. Celebrated on September 24th, Silouan experienced divine visions and taught the prayer 'Lord Jesus Christ, have mercy on me.' His spiritual notes, preserved by his disciple, reveal profound insights into Orthodox spirituality and the experience of God.

The commemoration of the finding of Christ's Cross by St. Helena and its elevation by St. Macarius for veneration. Celebrated on September 14th, this feast is both joyful (for the Cross's discovery) and solemn (remembering Christ's suffering). Flowers and basil are often blessed, and a strict fast is observed.

The first Orthodox martyrs in Alaska, killed while bringing Christianity to native peoples. Celebrated on July 2nd, these monks were part of the original mission to Alaska and were martyred by hostile natives who later converted to Orthodoxy. They represent the sacrifice required for missionary work and the eventual triumph of the Gospel message.

The 14th-century monk who founded the Trinity Lavra and renewed Russian monasticism. Celebrated on September 25th, Sergius established the monastery dedicated to the Trinity and inspired a spiritual revival in Russia. He blessed Prince Dmitri before the Battle of Kulikovo and represents the harmony between contemplative life and national service.

The Apostle and Evangelist John, author of the Fourth Gospel, three Epistles, and Revelation. Known as "the Theologian" for his profound spiritual insights and "the Beloved Disciple" for his closeness to Christ. Celebrated on May 8th, his feast honors his unique witness to Christ's divine nature and his care for the Theotokos.

The commemoration of the Virgin Mary's miraculous appearance in Constantinople, when she spread her veil over the praying Christians to protect them from enemies. Celebrated on October 1st, this feast is especially beloved in Slavic Orthodox churches. It emphasizes the Theotokos's continuing intercession and protection of the faithful.