The Feast of Holy Pentecost is celebrated 50 days after Easter and 10 days after Christ’s Ascension. It marks the moment the Holy Spirit descended upon the Apostles, fulfilling Jesus’ promise and revealing the Holy Trinity, according to goarch.com.
This event is recorded in Acts 2. As the Apostles gathered, a sound like a rushing wind filled the house, and tongues of fire appeared above each one. They began to speak in different languages, astonishing the crowds in Jerusalem, who were gathered for the Jewish Feast of Pentecost. Some were amazed, while others mocked them. Peter stood and preached about Jesus’ death and resurrection. Moved by his words, about 3,000 people were baptized that day, forming the early Church.
The icon of Pentecost, called The Descent of the Holy Spirit, shows the Apostles seated in unity with tongues of fire above their heads, symbolizing the Spirit’s power. Saint Paul and the four Evangelists are also depicted, representing the Church’s mission. At the bottom, a figure called “Cosmos” symbolizes the world once in darkness but now receiving the light of Christ’s teaching.
Orthodox Christians celebrate with Divine Liturgy on Pentecost Sunday, preceded by Vespers and Matins. A special Vespers service includes kneeling prayers, marking the end of the no-kneeling tradition during the Paschal season. The next day, Monday, honors the Holy Spirit as one in essence with the Father and the Son.
Pentecost is seen as the “birthday” of the Church, a celebration of the Spirit’s guidance, and the beginning of the Apostles’ mission to preach the Gospel to the world.
Source: goarch.org