Saint Faustina had recorded in her diary the specific devotion to Jesus, given to her by the Lord. She stated that anyone who participates in Mass and receives both the sacraments of Reconciliation and the Eucharist on Divine Mercy Sunday, is assured by Jesus of the full remission of their sins. In his encyclical on the Mercy of the Lord, Pope John Paul II developed and explained a spiritual and doctrinal basis for our faith in the mercy of God. By linking the revealed truth about God’s mercy to one of the most solemn Sundays after Easter itself, he illumined the fact that the liturgy already proclaimed the divine mercy. The truth has been embedded for two millennia in the worship of the Church.
“His mercy endures forever.” In the Gospel of John we remember that gift of “Peace” given to the disciples by the Risen Christ, showing the marks of His suffering and Passion, and demonstrating the saving grace and mercy of His death and resurrection. They, like ourselves, are filled with joy as He provides to the disciples the power of God’s mercy for the sinner, the gift and sacrament we know as Reconciliation: “Receive the holy Spirit. Whose sins you forgive are forgiven them, and whose sins you retain are retained.” Cardinal Justin Rigali of Saint Louis noted regarding Reconciliation, “This beautiful Sacrament was presented to the Church by Christ himself on the day of his Resurrection, hence this Sacrament of Mercy is supremely relevant also in this Easter season.”
Saint Augustine of Hippo about the Easter Octave, which he called "the days of mercy and pardon," and the Octave Day itself "the compendium of the days of mercy."
Thomas. We may struggle and fall. But we can remain confident in the Divine Mercy of the Lord, given to us in the Passion, Death, and Resurrection of Christ, and present in the sacraments. We need only look to the Eucharist for a vivid reminder of Our Lord’s unending mercy and love, both during the Easter season and throughout the year.