By John M. Grondelski, Crisis Magazine - Divine Mercy Sunday is April 8, 2018, the Octave Day of Easter. Devotion to Divine Mercy has been growing worldwide for many years and was added to the calendar of the universal Church in 2000, the year St. John Paul II canonized St. Faustina Kowalska... St. Faustina Kowalska was a nun who, in the 1930s, received a series of private revelations centered on God’s mercy as his greatest attribute.