STOCKBRIDGE, Mass. — Divine Mercy Sunday opens the “floodgates of mercy” for all through the sacraments of confession and holy Communion, said a priest renowned for promoting the liturgical feast and its accompanying devotion.

“A soul that’s been to confession and receives holy Communion (on that day) will receive this extraordinary promise that Jesus gave us … which is not only the complete forgiveness of all sin, but the remission of all punishment,” Father Chris Alar, provincial superior of the Marian Fathers of the Immaculate Conception of the Blessed Virgin Mary, told OSV News.

Observed on the second Sunday of Easter, Divine Mercy Sunday was established in 2000 by St. John Paul II during his canonization of St. Maria Faustina Kowalska, a 20th-century Polish mystic. As a Sister of Our Lady of Mercy, the unassuming saint shared how she enjoyed numerous visions in which Christ urged her to promote devotion to his mercy through various prayers, an annual feast, and an image featuring rays of blood and water issuing from his heart.

Father Alar said he and his fellow Marian priests are expecting more than 15,000 to attend an April 15-16 Divine Mercy Sunday weekend at the National Shrine of the Divine Mercy, located along with the order’s U.S. provincialate in Stockbridge, Massachusetts.

Atlanta Auxiliary Bishop Bernard E. Shlesinger III will celebrate the weekend’s April 16 liturgy at the site’s Mother of Mercy outdoor shrine. Along with Father Alar, speakers at the event will include Marian Fathers Donald Calloway and Joseph Roesch, author and radio host Michael O’Neill, and author Donna-Marie Cooper O’Boyle.

With the Catholic Church in the U.S. amid a National Eucharistic Revival, this year’s Divine Mercy Sunday gathering will explore the profound relationship between the Eucharist and the devotion to Divine Mercy, said Father Alar.

“All of the Divine Mercy devotion is focused on two very simple things: getting us back to the sacraments of confession and Communion,” he said. “And that’s the whole point.”

The grace and healing conferred by both sacraments are more needed than ever, he added.

“Scripture says that ‘where sin abounds, grace abounds more,’” said Father Alar, citing St. Paul’s Letter to the Romans (Rom 5:20). “God keeps heaping up mercy, because sin keeps getting worse and worse.”

According to the diary St. Faustina was instructed to keep by her spiritual director, Christ promised to grant to those who fulfill the Divine Mercy Sunday conditions complete forgiveness of sins, as well as remission of the temporal punishment they incur, “something we normally don’t get in the confessional,” said Father Alar.

 The Catechism of the Catholic Church (CCC) teaches that sin incurs a “double consequence” (No. 1472). If grave in nature, sin can result in eternal punishment, while temporal punishment — entailed in every sin, even venial — follows from an unhealthy attachment to creatures.

While the sacrament of reconciliation “(restores) us to God’s grace … joining us with him in intimate friendship” (CCC, No. 1468), the “temporal punishment of sin remains” (CCC, No. 1473), requiring purification through works of mercy, charity, prayer and penance to complete the soul’s conversion. Such temporal punishment can also be remitted, in whole or in part, through indulgences granted by the church — and through fulfilling the Divine Mercy Sunday conditions, said Father Alar.

“Normally, we are just forgiven of sins, but we have to still atone for the consequences,” he said. “But now, Jesus promises to wipe even that away. … He gives us this day to become spotless, to wipe clean all our past mess, our mistakes of the past.”

But there is one catch to that sweeping promise, Father Alar said.

 “Every other sin — lying, stealing, abortion, murder, adultery — is forgivable,” he said. “The Bible tells us there’s one unforgivable sin, and that sin is called the sin against the Holy Spirit,” described in Matthew 12:31-32.

“It simply means refusing to accept the mercy of God,” Father Alar said. “All you have to do is ask for it. … There’s nothing God can’t cleanse, clean, and forgive in you if you simply ask with a contrite heart. You will be forgiven no matter what. Jesus’ mercy is greater than any sin.”

Gina Christian is a national reporter for OSV News. Follow her on Twitter at @GinaJesseReina.