The "Descent of the Holy Spirit" refers to the event described in the New Testament when the Holy Spirit descended upon the apostles. This event occurred during the Jewish festival of Pentecost, which took place fifty days after Easter. The apostles were gathered in a room when they experienced a powerful wind and saw what appeared to be tongues of fire resting on each of them. As a result of this descent, the apostles began to speak in different languages, enabling them to communicate with people from various nations. This moment is often considered the birth of the Christian Church, as it empowered the apostles to spread the teachings of Jesus Christ to a wider audience.