My mercy is so great that no mind, be it of man or of angel, will be ale to fathom it throughout all eternity.
The Feast - Divine Mercy Sunday
Not only did Jesus ask for an image of Mercy to be painted, He asked that a Feast of Mercy be celebrated on the Sunday after Easter by all of the faithful...
"No soul will be justified until it turns with confidence to My mercy, and this is why the first Sunday after Easter is to be the Feast of Mercy. On that day, priests are to tell everyone about My great and unfathomable mercy." (Diary, 570)
"+Ask of my faithful servant [Father Sopocko] that, on this day, he tell the whole world of My great mercy; that whoever approaches the Fount of Life on this day will be granted complete remission of sins and punishment." (Diary, 300)
+Oh, how much I am hurt by a soul's distrust! Such a soul professes that I am Holy and Just, but does not believe that I am Mercy and does not trust in My Goodness. Even the devils glorify My Justice but do not believe in My Goodness. (Diary, 300)
+Mankind will not have peace until it turns with trust to My mercy.
...
My Heart rejoices in this title of Mercy. (Diary, 300)
We already know about God's mercy, right? Why, then, a feast?
"But, Jesus, I have one more word to say to You: I am very surprised that You bid me to talk about this Feast of Mercy, for they tell me that there is already such a feast and so why should I talk about it? And Jesus said to me, And who knows anything about this feast? No one! Even those who should be proclaiming My mercy and teaching people about it often do not know about it themselves. That is why I want the image to be solemnly blessed on the first Sunday after Easter, and I want it to be venerated publicly so that every soul may know about it." (Diary, 341)
Our Lord wants us to trust Him - to believe in His love and goodness. To help us embrace His Mercy and Love, He gave specific instructions for the faithful to follow on this day - a day of abundant graces!
"On one occasion, I heard these words: My daughter, tell the whole world about My inconceivable mercy. I desire that the Feast of Mercy be a refuge and shelter for all souls, and especially for poor sinners. On that day the very depths of My tender mercy are open. I pour out a whole ocean of graces upon those souls who approach the fount of My mercy. The soul that will go to Confession and receive Holy Communion shall obtain complete forgiveness of sins and punishment. On that day all the divine floodgates through which grace flow are opened. Let no soul fear to draw near to Me, even though its sins be as scarlet. My mercy is so great that no mind, be it of man or of angel, will be ale to fathom it throughout all eternity. Everything that exists has come forth from the very depths of My most tender mercy. Every soul in its relation to Me will contemplate My love and mercy throughout eternity. The Feast of Mercy emerged from My very depths of tenderness. It is My desire that it be solemnly celebrated on the first Sunday after Easter. Mankind will not have peace until it turns to the Fount of My Mercy. " (Diary, 699)
There is reason to rejoice in these messages to the world. But, there is also a sense of urgency ...
Jesus looked at me and said, Souls perish in spite of My bitter Passion. I am giving them the last hope of salvation; that is, the Feast of My Mercy. If they will not adore My mercy, they will perish for all eternity. Secretary of My mercy, write, tell souls about this great mercy of Mine, because the awful day, the day of My justice, is near. " (Diary, 965)
The Church has declared this day a special feast for the faithful, raised it to the universal calendar (all the parishes throughout the world celebrate it) and offers an indulgence:
"And so the Supreme Pontiff, motivated by an ardent desire to foster in Christians this devotion to Divine Mercy as much as possible in the hope of offering great spiritual fruit to the faithful, in the Audience granted on 13 June 2002, to those Responsible for the Apostolic Penitentiary, granted the following Indulgences:
a plenary indulgence, granted under the usual conditions (sacramental confession, Eucharistic communion and prayer for the intentions of Supreme Pontiff) to the faithful who, on the Second Sunday of Easter or Divine Mercy Sunday, in any church or chapel, in a spirit that is completely detached from the affection for a sin, even a venial sin, take part in the prayers and devotions held in honour of Divine Mercy, or who, in the presence of the Blessed Sacrament exposed or reserved in the tabernacle, recite the Our Father and the Creed, adding a devout prayer to the merciful Lord Jesus (eg Merciful Jesus, I trust in you!");
A partial indulgence, granted to the faithful who, at least with a contrite heart, pray to the merciful Lord Jesus a legitimately approved invocation."
**From: APOSTOLIC PENITENTIARY DECREE: Indulgences attached to devotions in honour of Divine Mercy
Read the Apostolic Decree regarding Divine Mercy and the indulgences granted for this feast!
https://www.ewtn.com/devotionals/mercy/feast.htm