Although this holiday began as a harvest festival in the calendar of ancient Israel and is still celebrated as Shavuot in Judaism, in the Christian liturgical year, it became a feast commemorating the descent of the Holy Spirit upon the Apostles and other followers of Jesus Christ, as described in the Acts of the Apostles 2:1–31. For this reason, Pentecost is often described by Christians today as the "Birthday of the Church."
This banner was displayed in our sanctuary today. I have cropped the stand and trappings to emphasize the contemporary design in the center.