The main sign of Pentecost is the color red. It symbolizes joy and the fire of the Holy Spirit. Priests or ministers, and choirs wear red vestments, and in modern times, the custom has extended to the lay people of the congregation wearing red clothing in celebration as well.
And when the days of Pentecost were drawing to a close, they were all together in one place. And suddenly there came a sound from heaven, as of a violent wind coming, and it filled the whole house where they were sitting. And there appeared to them parted tongues as of fire, which settled upon each of them. And they were all filled with the Holy Spirit and began to speak in foreign tongues, even as the Holy Spirit prompted them to speak .
Pentecost (Whitsunday), with Christmas and Easter, ranks among the great feasts of Christianity. It commemorates not only the descent of the Holy Spirit upon the Apostles and Disciples, but also the fruits and effects of that event: the completion of the work of redemption, the fullness of grace for the Church and its children, and the gift of faith for all nations. The reason is that Pentecost is the fiftieth day after Easter Sunday and the final day of the Easter season. As one of the most important solemnities on the Church's calendar, it has a rich depth of meaning, but here is how Pope Benedict summarized it in 2012: This Solemnity makes us remember and relive the outpouring of the Holy Spirit on the Apostles and the other disciples gathered in prayer with the Virgin Mary in the Upper Room Jesus, risen and ascended into Heaven, sent his Spirit to the Church so that every Christian might participate in his own divine life and become his valid witness in the world. The Holy Spirit, breaking into history, defeats aridity, opens hearts to hope, stimulates and fosters in us an interior maturity in our relationship with God and with our neighbour.
Happy Birthday, Church
It was right after Pentecost that Peter, inspired by the Holy Spirit, preached his first homily to Jews and other non-believers, in which he opened the scriptures of the Old Testament, showing how the prophet Joel prophesied events and the coming of the Holy Spirit at Pentecost. He also tells the people that the Jesus they crucified is the Lord and was raised from the dead, which “cuts them to the heart.” When they asked what they should do, Peter exhorts them to repent of their sins and to be baptized. According to the account in Acts, about 3,000 people were baptized following Peter’s sermon. For this reason, Pentecost is considered the birthday of the Church - Peter, the first Pope, preaches for the first time and converts thousands of new believers. The apostles and believers, for the first time, were united by a common language, and a common zeal and purpose to go and preach the Gospel.