The Need to Pray for Sinners
In the message given to St. Faustina, Jesus emphasises many times the need to pray for sinners: "The loss of each soul plunges Me into mortal sadness. You always console Me when you pray for sinners. The prayer most pleasing to Me is prayer for the conversion of sinners" (Diary 1397). "Gather all sinners from the entire world and immerse them in the abyss of My mercy" (Diary 206).
Jesus' also requests prayer for the dying, "By your prayers, obtain for them trust in My mercy, because they have most need of trust, and have it least. Be assured that the grace of eternal salvation for certain souls in their final moment depends on your prayer"(Diary 1777).
He also allowed St. Faustina to visit Purgatory because He wanted her to pray for the dead and perform deeds of mercy for them, bringing them relief in their suffering while in Purgatory.How to Pray for Sinners
Jesus also tells us how we should pray for souls, which is that we should become united with Him through love and through everything that makes up our everyday human life. We should also take part in His salvific work. He instructed St. Faustina, "You will join prayers, fasts, mortifications, labours and all sufferings to My prayer and sufferings and then they will have power before My Father".(Diary 531)
The Value of our Personal Suffering
A special role in entreating God's mercy for the world is played by suffering. "There is but one price at which souls are bought”, Jesus told St. Faustina, “and that is suffering united to My suffering on the cross" (Diary 324).
"Every conversion of a sinful soul demands sacrifice" (Diary 961). The Lord Jesus told St. Faustina: "I have need of your sufferings to rescue souls” (Diary 1612).”Help Me, My daughter to save souls. Join your sufferings to My Passion and offer them to the Heavenly Father for sinners" (Diary 1032).
St. Faustina's Perfect Example
St. Faustina had magnanimously undertook this task, providing an example for the future apostles of Divine Mercy Devotion. "O my God”, she wrote, “I am conscious of my mission in the Holy Church. It is my constant endeavour to plead for mercy for the world. I unite myself closely with Jesus and stand before Him as an atoning sacrifice on behalf of the world" (Diary 482). "I am being burned up by the desire to save souls; I traverse the world's length and breadth ... to save souls. I do this through prayer and sacrifice"(Diary 745). By cooperating with Jesus in the task of saving lost souls, she offered her life in sacrifice for sinners and particularly for those souls who have lost hope in God's mercy (Diary 309). Her life was a continual sacrifice and that is why she was able to write, "My name is host” (Diary 485).
The task of entreating God's mercy for the world is taken up in a very special way by the "Sisters of Merciful Jesus" founded in Vilnius by Saint Faustina on request of Our Lord. "Souls separated from the world”writes St. Faustina “will burn as an offering before God's throne and beg for mercy for the whole world ... and by their entreaties they will obtain blessings for priests and through their prayers prepare the world for the final coming of Jesus" (Diary 1155).
On the other hand, active congregations are to combine prayer with deeds of mercy. The remaining members of the Apostolic Movement of the Divine Mercy are to act in a similar way in as far as is only in their might. Yet, a special appeal is addressed by St. Faustina to the religious, when she writes in the summing up of the order of the new congregation,"Oh, how great should be the ardour of every soul who will live in that convent. Let everyone remember that if we religious do not intercede before God, who will? (Diary 572).
The Devotion to Divine Mercy
It is also the same cause, namely that of entreating God's mercy for the whole world, that the new forms of devotion revealed to St. Faustina are to serve. They are to be the vessels by means of which we are to draw graces of God's mercy, as well as an instrument of "appeasing God's wrath". (Diary 476)
At the very foundation of each of the above-mentioned tasks lies a genuine acquaintance with and personal experience of the mystery of God's mercy. For it is on this experience that there depends one's spiritual revival, and thereby one's growth in the attitude of entrustment to God and mercy towards neighbours. It is also on this experience that there depends the effectiveness of one's apostolic activity, that is proclaiming the mystery of the Mercy of God revealed in Christ crucified and risen as well as the intensity of prayer and sacrifice in the intention of entreating mercy for oneself and for the world.
Source: Divine Mercy Apostolate Worlwide