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 soldier-saint martyred under Diocletian, venerated as the 'Trophy-Bearer' for his victory over evil. Celebrated on April 23rd, George is patron of soldiers, England, and Georgia. The legend of his slaying a dragon symbolizes triumph over evil. His courage in maintaining faith despite torture makes him a model of Christian fortitude.

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 evangelist who wrote the shortest Gospel, emphasizing Christ's divine power through miracles. Celebrated on April 25th, Mark was a companion of both Peter and Paul. He founded the Church in Alexandria and is patron of Venice. His Gospel, likely the first written, served as a source for Matthew and Luke.

The Archbishop of Caesarea and one of the Three Holy Hierarchs, defender of Orthodox theology against Arianism. Celebrated on January 1st, Basil wrote the Divine Liturgy bearing his name and established principles of monasticism. His work on the Trinity and pastoral care shaped Orthodox theology and practice for centuries.

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 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 "Apostles to the Slavs" who brought Christianity and literacy to Slavic peoples in the 9th century. Celebrated on May 11th, these brothers created the Glagolitic alphabet and translated the Bible and liturgy into Old Church Slavonic. Their missionary work established Orthodox Christianity among the Bulgarians, Moravians, and other Slavic nations.

The day after Pentecost, continuing the celebration of the Holy Spirit's descent upon the Church. Also called 'Trinity Monday,' this feast honors the Third Person of the Trinity specifically. Many Orthodox churches hold special services with kneeling prayers, emphasizing the ongoing work of the Spirit in the Church and in believers' lives.

The Tuesday after Pentecost, continuing the celebration of the Trinity and the gift of the Holy Spirit. This day maintains the festal character of the Pentecost season with special hymns and prayers. Many Orthodox communities hold additional services during Trinity Week to honor the complete revelation of the Triune God.

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.