On the day of Pentecost when the seven weeks of Easter had come to an end, Christ's Passover is fulfilled in the outpouring of the Holy Spirit, manifested, given, and communicated as a divine person: of his fullness, Christ, the Lord, pours out the Spirit in abundance. With the outpouring of the Holy Spirit, the Church is born. The mission of Christ and the Holy Spirit is brought to completion in the Church, which is the Body of Christ and the Temple of the Holy Spirit.
By this power of the Spirit, God's children can bear much fruit. The Church's mission is not an addition to that of Christ and the Holy Spirit, but is its sacrament: in her whole being and in all her members, the Church is sent to announce, bear witness, make present, and spread the mystery of the communion of the Holy Trinity.
Through the Holy Spirit we are restored to paradise, led back to the Kingdom of heaven, and adopted as children, given confidence to call God "Father" and to share in Christ's grace, called children of light and given a share in eternal glory.
- The Catechism of the Catholic Church