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.

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 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.