Pentecost is the celebration of the person of the Holy Spirit coming upon the Apostles, Mary, and the first followers of Jesus, who were gathered together in the Upper Room.
A “strong, driving” wind filled the room where they were gathered, and tongues of fire came to rest on their heads, allowing them to speak in different languages so that they could understand each other. The image shows our statue of Saint Jude (who was present) with the tongue of fire on his head.
It was such a strange phenomenon that some people thought the Christians were just drunk - but Peter pointed out that it was only the morning, and that the phenomenon was caused by the Holy Spirit.
The Holy Spirit also gave the apostles the other gifts and fruits necessary to fulfill the great commission - to go out and preach the Gospel to all nations. It fulfills the New Testament promise from Christ (Luke 24:46-49) that the Apostles would be “clothed with power” before they would be sent out to spread the Gospel.
Saint Jude went out and spread the Good News of the Lord.