After Easter and Christmas, Pentecost Sunday is the next most important feast of the Church’s year. It is sometimes referred to as the birthday of the Church, for it is the day on which the Church truly came alive.
The Twelve had been with Him since shortly after His baptism. They had listened to His words, seen Him multiply bread and fish to feed the crowd, change water into wine, heal the blind, the deaf, the paralyzed, those possessed by demons, and raise the dead to life. They had eaten with Him at the Last Supper, witnessed His Crucifixion and Resurrection, and been with Him for 40 days in His risen state.