In 1931 a Sr. Faustina Kowalska of the Congregation of Sisters of Our Lady of Mercy received apparitions of the Lord Jesus. According to her diary, an image of the Risen Lord was revealed to her. From his heart shone two rays, one red (representing blood) and the other “pale” (symbolizing water), beneath of which were the words “Jesus, I trust in you.” Jesus told her, “I promise that the soul that will venerate this image will not perish.”
At Sr. Faustina’s canonization in 2000, Pope John Paul II, proclaimed that the Second Sunday of Easter would also be known as Divine Mercy Sunday, thus promoting the devotional practices associated with Faustina’s visions.
St. Faustina’s diary entries focus on God’s mercy, the call to accept God’s mercy, to be merciful, the need for conversion, and the call to trust in Jesus. It had been Jesus’ own wish, she wrote, to establish a feast day: “I [Jesus] desire that the Feast of Mercy be a refuge and shelter for all souls. . . . I am giving them the last hope of salvation; that is, the Feast of My Mercy.”
Among the practices connected to the devotion are its Novena, the Chaplet of the Divine Mercy, the Hour of Great Mercy (traditionally celebrated at 3 p.m.), and the plenary indulgence granted to those who make a Sacramental Confession and receive Holy Communion on Divine Mercy Sunday.
Divine Mercy Sunday is an opportunity to reflect on how God’s mercy can overcome sin and as a recurrent invitation to face, with confidence in divine goodness, the difficulties and trials to come.
Edited: May 2011 issue of U.S. Catholic (Vol. 76, No. 5, page 46)
For more information on the Divine Mercy devotions, see the Divine Mercy page under Worship & Liturgy > Devotions.
You can also read The Diary of Sr. Faustina. to learn about her life and what Jesus told her. It's very inspirational!