From Pope St. John Paul II’s Apostolic Exhortation Reconciliatio et Pænitentia (1984):
Thus the word of Scripture, as it reveals to us the mystery of pietas, opens the intellect to conversion and reconciliation, understood not as lofty abstractions but as concrete Christian values to be achieved in our daily lives.
Deceived by the loss of the sense of sin and at times tempted by an illusion of sinlessness which is not at all Christian, the people of today too need to listen again to St. John’s admonition, as addressed to each one of them personally: “If we say we have no sin, we deceive ourselves, and the truth is not in us,”110 and indeed, “the whole world is in the power of the evil one.”111 Every individual therefore is invited by the voice of divine truth to examine realistically his or her conscience and to confess that he or she has been brought forth in iniquity, as we say in the Miserere psalm.112
Nevertheless, though threatened by fear and despair, the people of today can feel uplifted by the divine promise which opens to them the hope of full reconciliation.
The mystery of pietas, on God’s part, is that mercy in which our Lord and Father—I repeat it again—is infinitely rich.113 As I said in my encyclical on the subject of divine mercy,114 it is a love more powerful than sin, stronger than death. When we realize that God’s love for us does not cease in the face of our sin or recoil before our offenses, but becomes even mere attentive and generous; when we realize that this love went so far as to cause the passion and death of the Word made flesh who consented to redeem us at the price of his own blood, then we exclaim in gratitude: “Yes, the Lord is rich in mercy,” and even: “The Lord is mercy.”
The mystery of pietas is the path opened by divine mercy to a reconciled life.
110 1 Jn 1:8.
111 1 Jn 5:19.
112 Cf Ps. 51(50):5.
113 Cf Eph. 2:4.
114 Cf Pope John Paul II, Dives in Misericordia, 8; 15: Acta Apostolicæ Sedis 72 (1980), 1203-1207; 1231.
— Reconciliatio et Pænitentia 22