On May 19 (Sunday), the Catholic Church celebrates the solemnity of Pentecost, commemorating the descent of the Holy Spirit on Mary, the mother of Jesus, and the Apostles. Fifty days after the Resurrection of the Lord, the Holy Spirit descended on the Apostles gathered in the upper room, just as Jesus had announced before the Ascension.
Why Pentecost?
The Feast of the Holy Spirit is celebrated on the fiftieth day after the Resurrection of the Lord. In liturgical language, the feast of Pentecost is called "Pentecost" for this reason. The Greeks had their own word for it – Pentecostes, or fifty. Latin has taken over the word by using "Pentecoste". This is not without significance for contemporary Catholics – the entire Anglo-Saxon world celebrates a holiday called Pentecost in this language, although in English, of course, it does not mean the same as "fifty". The Italians, on the other hand, celebrate the Pentecoste feast – they have not changed the Latin original. We have "Pentecost".
It is one of the three most important celebrations in the liturgical year.
The three greatest celebrations of the ecclesiastical year are dedicated to the three Persons of the Most Holy Trinity: Christmas is the feast of God the Father because it celebrates God's Fatherhood – the Eternal Father sends His only-begotten Son to earth to redeem sinful humanity. Easter is the feast of God the Son, who, after his passion and death on the cross, crowned the work of Redemption with the glorious Resurrection. Finally, Pentecost is the feast of the third divine Person, the Holy Spirit, whom the Father and the Son send into the world so that what the Father created and the Son redeemed may be confirmed and sanctified by Him.
On this day, the Church was born
According to many Catholic writers, Pentecost is considered the day of the birth of the Church. The three thousand converts mentioned above multiplied with astonishing speed. It did not take fifty years from the day of Pentecost for the holy name of Jesus Christ to be heard in every corner of the world known to man at that time.
St. John Paul II wrote that although the Church was born on the cross on Good Friday, it remained hidden. He decided to reveal its birth to the world fifty days later. On that day, he was born for the whole world.