The date changes from year-to-year, but is always the first Sunday after Easter.
"For those who followed John Paul II's pontificate, it is a special Sunday," said Fr. Lombardi.
It is a "fundamental date in his life and his encounter with the Lord," the Vatican spokesman said. He explained that it is the day the Church celebrates the apparition of Jesus to the disciples in the upper room and the institution of Confession.
The day was particularly important to the late-pontiff because it was the day in 2000 that he celebrated the canonization of St. Faustina Kowalska and declared that the Sunday after Easter should henceforth be known as "Divine Mercy Sunday."
Sister Faustina, known for promoting the Divine Mercy chaplet, which is prayed using a rosary, said that all who go to Confession and receive the Eucharist at Mass the Sunday after Easter will be given full remission of their sins.
Divine Mercy is "absolutely fundamental" to the pontificate of John Paul II.
"It's precisely the vision, we could say, of the pontificate of John Paul II that has this theme of the Divine Mercy," Fr. Lombardi said.
The staff at St. Peter's Basilica is already preparing for what is sure to be a grand occasion, drawing pilgrims from all over the globe. Workers are already cleaning the mosaics in the Chapel of St. Sebastian, just next to Michelangelo's Pietà, where the soon-to-be "blessed's" body will lie.
John Paul II's body will be taken from the crypt below and set below the chapel's altar.
Because the process came about so quickly after his death, Fr. Lombardi said that the body will not be exhumed for examination.
A marble stone bearing his name "Beatus Iovannes Paulus" will adorn the coffin.
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The body will not be exposed, as others are in the basilica, "at least not for now," said Fr. Lombardi.
Blessed Pope Innocent XI's tomb, currently found below the altar in the same chapel, will be moved nearer the high altar of St. Peter's to make room for the new tenant. His body will be put under the altar located below the famous mosaic rendering Raphael's The Transfiguration.
The transfer will take place some time before the May 1 beatification, said Fr. Lombardi. He said that other logistical details have yet to be decided for the celebration.
During his audience with Cardinal Amato, Pope Benedict also approved two miracles attributed to other figures, recognized the martyrdom of five religious sisters from Bosnia/Herzogovina, and certified that "heroic virtue" was found in the lives of five other candidates for sainthood.
One of the five who were seen to have exhibited extraordinary virtue in their lives is Fr. Nelson Baker of Buffalo, New York. He spent much of his 95 years of life in service to orphaned children.
In an interview with Vatican Radio, the prefect of the Vatican's office for the causes of saints said that all "are fascinating figures whose fame of saintliness is widespread in their countries of origin and who always constitute very current examples in their evangelical testimony."