Today, according to the Gregorian calendar, is the Second Sunday of Pascha. As such, it is St. Thomas Sunday, the Gospel reading for which describes the encounter between Thomas, who refused to believe the resurrection until he had seen and touched the risen Jesus for himself (St. John 20:24-29) It is also Divine Mercy Sunday, a celebration in the Roman Church promulgated by the late Pope, John Paul II, on the basis of a series of private revelations given an early 20th Century Polish sister, St. Faustina. Rocco Palmo writes about Divine Mercy Sunday in the following:
The Quality of Mercy
Of course, the great sign of God's infinite mercy is the cross of our Lord Jesus Christ. In the Byzantine Orthodox Churches, still journeying through Lent, today is the Sunday of the Cross, of which Fr. Stephen writes here.