Pentecost.
The Holy Spirit came with power upon the disciples 10 days after the ascension on the Day of Pentecost.
The Solemnity of the Ascension is on Thursday, forty days after Easter, it celebrates Our Blessed Lord's ascension into heaven, and is followed ten days later by Pentecost when He sends the Holy Spirit down on His Church. The Ascension may be transferred to the Sunday before Pentecost in some dioceses.
The Pentecost is a Christian holiday that commemorates the descent of the Holy Spirit upon the disciples of Jesus after his Ascension.
Pentecost was the birth of the church. Also, Jesus used Pentecost to give Believers the Holy Spirit.
Pentecost is the feast which celebrates the coming of the Holy Spirit upon the Blessed Virgin Mary and the Apostles nine days after Our Blessed Lord's ascension into heaven. It is rightly called the birthday of the Church because, with the coming of the Holy Spirit, the apostles were no longer frightened, timid men in the upper room. They now had the courage of their convictions and were out preaching and baptizing by the thousands.
The 'birthday' of the Church, as at Pentecost the Holy Spirit came upon the disciples of Jesus and after that moment they began to go out and preach the gospel, forming the Christian Church
To signify the Fire Of the Holy Spirit.
The Church began on Pentecost Sunday when the Holy Spirit descended upon the apostles.
Pentecost commemorates the day that the Holy Spirit descended upon the Apostles, prompting them to begin evangelizing. It is the birthday of the Church. Had Pentecost never occurred, there would be no Christian Church today.
Easter, also known as the Resurrection of Jesus, is considered the most important feast of the Church year by many Christians. It commemorates the central event of the Christian faith - the resurrection of Jesus Christ from the dead. Easter is a time of joy and celebration for Christians around the world.
On the Day of Pentecost, when the Apostles received the Seal of the Holy Spirit.
The Catholic Church began at Pentecost with the coming of the Holy Spirit "like the rush of a mighty wind" on the Apostles in the upper room, read the second chapter of Acts.