"Even if our sins were as black as night, divine mercy is stronger than our misery," the Pope said, echoing Sister Faustina Kowalska, one of his favorite saints.
"Only one thing is necessary: that the sinner at least leave the door of his heart ajar, the rest will be done by God. Everything begins and ends in your mercy," the Pope added, as he commented on Psalm 50 to thousands of pilgrims gathered in St. Peter´s Square.
The Holy Father was continuing a yearlong series of meditations on the Psalms.
Psalm 50 is a poetic composition attributed to David´s adultery with Bathsheba and the killing of her husband Uriah.
The Miserere, as it is also known, begins by showing the malice of sin ("Against you alone have I sinned; I have done such evil in your sight"), which distances man from God and his brothers. The Psalm also shows how when "man confesses his sin, God´s salvific justice is ready to purify him radically," the Holy Father said.
"In fact, through confession of faults, for the man of prayer a horizon of light opens, where God is at work," the Pope explained. "The Lord does not just act negatively, eliminating sin, but re-creates sinful humanity through his vivifying Spirit: He infuses a new and pure heart in man, namely, a renewed conscience, and opens the possibility of a limpid faith and worship that is pleasing to God."
Recognition of one´s own sin, conversion and God´s forgiveness are "fundamental components of a spirituality that should reverberate in the daily life of the faithful," John Paul II concluded.