The picture to the left is the Church of Divine Mercy in Krakow Poland. The Triduum of Holy Week, along with the entire Easter season, focuses on various aspects of the paschal mystery. Holy Thursday celebrates the Mass of the Chrism and the evening Mass of the Mandatum - the washing of the feet of the disciples, ordination to the priesthood, the institution of the Eucharist, and the last discourse of Our Lord promising the sending of the Holy Spirit. Good Friday commemorates the passion and death of Jesus on the cross. The Easter vigil, the pinnacle of the paschal mystery, celebrates the fulfillment of the prophecies of the Redeemer who is our light and salvation, bringing us new life by water and the Holy Spirit. The Easter season continues this celebration, leading to the Ascension of the Lord and to Pentecost - the fulfillment of the promise to send the Holy Spirit.
The Feast of Mercy focuses on God's mercy as an event! It focuses on God's continuing action of mercy throughout salvation history as we see it recorded in the letter to the Romans, chapters 9, 10,11, culminating in His loving plan to have mercy on all! (See Rom 11:32.) This Feast is a summation of the event to His mercy active in our lives now. It is because of His mercy that we have forgiveness of sin and new life as children of God. This needs to be celebrated!