foundation · 30 · Jerusalem
On the fiftieth day the sound of a rushing wind filled the house, tongues as of fire rested on each, and Galileans preached to pilgrims of every nation in their own languages. Peter stood up with the Eleven; about three thousand were baptized. The church counts its birthdays from this morning.
Pentecost is a Christian holiday that takes place on the 49th day after Easter. It commemorates the descent of the Holy Spirit upon the Apostles of Jesus, Mary, and other followers of Christ, while they were in Jerusalem celebrating the Feast of Weeks, as described in the Acts of the Apostles. Pentecost marks the "Birthday of the Church".
The Spirit descends; the church goes public in every tongue.