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.1
On that day, the Holy Trinity is fully revealed. Since that day, the Kingdom announced by Christ has been open to those who believe in him: in the humility of the flesh and in faith, they already share in the communion of the Holy Trinity. By his coming, which never ceases, the Holy Spirit causes the world to enter into the “last days,” the time of the Church, the Kingdom already inherited though not yet consummated.
We have seen the true Light, we have received the heavenly Spirit, we have found the true faith: we adore the indivisible Trinity, who has saved us.
“God is Love” and love is his first gift, containing all others. “God’s love has been poured into our hearts through the Holy Spirit who has been given to us.”
Because we are dead or at least wounded through sin, the first effect of the gift of love is the forgiveness of our sins. the communion of the Holy Spirit in the Church restores to the baptized the divine likeness lost through sin.
He, then, gives us the “pledge” or “first fruits” of our inheritance: the very life of the Holy Trinity, which is to love as “God (has) loved us.” This love (the “charity” of ⇒ 1 Cor 13) is the source of the new life in Christ, made possible because we have received “power” from the Holy Spirit.
By this power of the Spirit, God’s children can bear much fruit. He who has grafted us onto the true vine will make us bear “the fruit of the Spirit: . . . love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control”. “We live by the Spirit”; the more we renounce ourselves, the more we “walk by the Spirit.”
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.
From the Catechism of the Catholic Church 731- 736