On this "Divine Mercy Sunday" -- the annual feast instituted by John Paul II to honor the visions of the Polish mystic.

Sr Faustina Kowaklska, who the late pontiff canonized -- Benedict XVI paid tribute to his predecessor and the devotion at today's Regina Caeli:

“Mercy,’ said Benedict XVI, ‘is in reality the core of the Evangelical message; it is the name of God itself, the face with which He revealed Himself in the Ancient Covenant and fully in Jesus Christ, incarnation of Creative and Redemptive Love. This love of mercy illuminates the face of the Church as well, and manifests itself via the Sacraments, in particular that of the Reconciliation, and charity, community and individual works. All that the Church says and does is a manifestation of God’s mercy for man.