"I will pour out my Spirit." God’s Old Testament people celebrated the gathering of the harvest at the Festival of Weeks, or the Festival of Pentecost. In the New Testament, God sent the promised Counselor on the day we call “Pentecost,” Greek for “fifty,” because he sent the Holy Spirit fifty days after the Resurrection. This day marked the birthday of the New Testament Church and celebrates the harvest of souls won by the Son and gathered by his servants empowered by his Spirit.
Pentecost is the third great festival (Nativity, Resurrection, Pentecost) of the Church and has been commemorated since at least 217 A.D. The Church dresses in red to remind us of the tongues of fire that marked the Spirit’s gift and the blood of the martyrs which was the seed of the Church. This day culminates the Season of Easter when our risen Lord now empowers his people to be witnesses of the resurrection for the world.