Divine Mercy Sunday, 7 Days After Easter (Western)

Divine Mercy Sunday is fixed by this rule seven days after Easter, the Sunday that closes the Easter Octave, a date the Western liturgical calendar had already marked for centuries as Low Sunday or Thomas Sunday, named for the Gospel account of the apostle Thomas examining Christ's wounds a week after the resurrection. The Divine Mercy title and the devotion it carries are recent by comparison, established by Pope John Paul the Second in the year two thousand, at the canonization of the Polish nun Faustina Kowalska, whose reported visions and diary describe Christ requesting that this Sunday specifically be kept as a feast of his mercy.

The choice of date was not arbitrary. The Thomas Sunday Gospel already read on this day, an encounter with a doubting apostle met by a wounded but merciful Christ, gave the new devotion a text already sitting on the calendar that could carry its theme without displacing anything, one of the clearer instances of a modern devotion being layered onto an existing date rather than requiring a new one of its own. The observance is specifically Catholic, tied to Faustina's canonization and to devotional practices, such as the Divine Mercy chaplet, that grew out of her writings, and it carries no equivalent in Orthodox or Protestant calendars, which keep the same Thomas Sunday Gospel on the same date without the added devotion.