What event does the Christian holiday of Pentecost commemorate?

The Christian holiday of Pentecost commemorates the descent of the Holy Spirit upon the apostles and other followers of Jesus. This event is significant as it marks the moment when the apostles were empowered to begin their mission of spreading the message of Jesus after his ascension into heaven. This event is described in the Book of Acts, specifically Acts 2, where it is detailed that the apostles were filled with the Holy Spirit, allowing them to speak in various languages and boldly proclaim the teachings of Christ. This moment is often considered the "birthday of the Church," as it represents the beginning of the apostles' public ministry and the establishment of the Christian community.

The other events listed, such as the birth of Jesus, the Last Supper, and the resurrection of Jesus, are important milestones in Christian tradition, but they do not pertain to Pentecost. The birth of Jesus is celebrated during Christmas, the Last Supper is commemorated on Maundy Thursday during Holy Week, and the resurrection of Jesus is celebrated at Easter. Each of these events holds its own significance within the Christian calendar, but none specifically represents the outpouring of the Holy Spirit that Pentecost signifies.