The life of a Christian should be the faithful reproduction of Jesus in their soul — this radiant transformation is the work of love of the Holy Spirit. “Those whom He had foreknown He has also predestined to become conformed to the image of His Son.” (Rom 8:29) He who loves will resemble the thing loved.

“God’s love has been poured into our hearts through the Holy Spirit who has been given to us.” (Rom 5:5) “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 (2 Cor 13:14) in the Church restores to the baptized the divine likeness lost through sin.” (CCC 734) The Holy Spirit perfects the soul with the first fruits of eternal glory: charity, joy, peace, patience, kindness, goodness, generosity, gentleness, faithfulness, modesty, self-control, and chastity — so we may more closely resemble Jesus Christ.
In his classic work on the Holy Spirit, The Sanctifier, Archbishop Luis M. Martinez reminds us that in order to resemble Christ, Our Lord, we must go through the pain and suffering of the Cross: “He whom we love is a God nailed to a cross. Pain makes us resemble him. It is characteristic of love to have a tremendous desire to resemble the beloved. It is characteristic, too, for those who love to resemble each other.” But, as the soul is transformed, it is also filled with joy!
After Christ had completed his mission on earth, it still remained necessary for us to become sharers in the divine nature of the Word. We had to give up our own life and be so transformed that we would begin to live an entirely new kind of life that would be pleasing to God. This was something we could do only by sharing in the Holy Spirit. As St. Paul writes: “But we all with unveiled faces, reflecting as in a mirror the glory of the Lord, are being transformed into His very image from glory to glory.” (2 Cor 3:18)
— St. Cyril of Alexandria
This is the work of the Holy Spirit of Love, who is the the light and fire of the Face of God: to sanctify our souls, shining upon us the radiance of His light, transforming us into the His own likeness. Holy Spirit wants to dwell in us and convert our bodies into His temple, as He did in the Virgin Mary to bring grace, mercy, and peace. “Love is not a passing visitor who pays us a call and then goes away. He establishes in us his permanent dwelling and lives in intimate union with our souls as their eternal Guest.” (The Sanctifier) As Jesus promised on the last night of His mortal life: “And I will ask the Father and He will give you another Advocate to dwell with you forever, the Spirit of truth whom the world cannot receive, because it neither sees Him nor knows Him. But you shall know Him because He will dwell with you and be in you.” (Jn 14: 16-17)
To Mary, Spouse of the Holy Spirit, Daughter of the Most High, Mother of God, faithful Spouse of the Holy Spirit — yet also Mary of Nazareth, Joseph’s wife, my mother– hear my prayer for grace, O Full of Grace. Pray your Spouse the Holy Spirit to come upon me — to shelter from all ill, to strengthen me to do what is right, to teach me all truth. Pray him come to me, and abide with me, and be within me a fountain springing up unto eternal life. May he sustain me in sorrow, sanctify me in life, and receive me at the hour of my death. Holy Mary, Mother of God, Mother of the Church, pray for us.