At the climax of Jesus’ messianic mission, the Holy Spirit becomes present in the Paschal Mystery in all his divine subjectivity: as the one who is now to continue the salvific work rooted in the sacrifice of the Cross.
[...] The words of the Risen Christ on the “first day of the week” give particular emphasis to the presence of the Paraclete-Counselor as the one who “convinces the world concerning sin, righteousness and judgment.”
For it is only in this relationship that it is possible to explain the words which Jesus directly relates to the “gift” of the Holy Spirit to the Apostles.
He says: “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained.”
Jesus confers on the Apostles the power to forgive sins, so that they may pass it on to their successors in the Church, but this power granted to men presupposes and includes the saving action of the Holy Spirit.
By becoming “the light of hearts,” that is to say the light of consciences, the Holy Spirit “convinces concerning sin,” which is to say, he makes man realize his own evil and at the same time directs him toward what is good.
Thanks to the multiplicity of the Spirit’s gifts, by reason of which he is invoked as the “sevenfold one,” every kind of human sin can be reached by God’s saving power.
In reality – as St. Bonaventure says – by virtue of the seven gifts of the Holy Spirit all evils are destroyed and all good things are produced.
Thus the conversion of the human heart, which is an indispensable condition for the forgiveness of sins, is brought about by the influence of the Counselor.
Without a true conversion, which implies inner contrition, and without a sincere and firm purpose of amendment, sins remain “unforgiven,” in the words of Jesus, and with him in the Tradition of the Old and New Covenants.
For the first words uttered by Jesus at the beginning of his ministry, according to the Gospel of Mark, are these: “Repent, and believe in the Gospel.”
A confirmation of this exhortation is the “convincing concerning sin” that the Holy Spirit undertakes in a new way by virtue of the Redemption accomplished by the Blood of the Son of Man.
Hence the Letter to the Hebrews says that this “blood purifies the conscience.”
It therefore, so to speak, opens to the Holy Spirit the door into man’s inmost being, namely into the sanctuary of human consciences.
John Paul II (1920-2005): Dominum et Vivificantem, 2,5,42.