Pentecost Sunday is one of the most ancient feasts of the Church. The Acts of the Apostles recounts the story of the original Pentecost (Acts 2). Jews from all over were gathered in Jerusalem to celebrate the Jewish feast. On that Sunday, ten days after the Ascension of Our Lord, the Apostles and the Blessed Virgin Mary were gathered in the Upper Room, where they had seen Christ after His Resurrection. Christ had promised His Apostles that He would send His Holy Spirit and, on Pentecost, they were granted the gifts of the Spirit. The Apostles began to preach the Gospel in all of the languages that the Jews who were gathered there spoke, and about 3,000 people were converted and baptized that day. That is why Pentecost is often called “the birthday of the Church.” On this day, with the descent of the Holy Spirit, Christ’s mission
is completed, and the New Covenant is established.