A plenary indulgence (the forgiveness of all temporal punishment from sins that have already been confessed) is granted on the Feast of Divine Mercy to all the faithful who go to Confession, receive Holy Communion, pray for the intentions of the Holy Father, and "in any church or chapel, in a spirit that is completely detached from the affection for a sin, even a venial sin, take part in the prayers and devotions held in honor of Divine Mercy, or who, in the presence of the Blessed Sacrament exposed or reserved in the tabernacle, recite the Our Father and the Creed, adding a devout prayer to the merciful Lord Jesus (e.g. 'Merciful Jesus, I trust in you!').
A partial indulgence (the remission of some temporal punishment from sin) is granted to the faithful "who, at least with a contrite heart, pray to the merciful Lord Jesus a legitimately approved invocation."
"...Private revelations often spring from popular piety...This does not exclude that they will have an effect even on the liturgy, as we see...in the feasts of Corpus Christi and of the Sacred Heart. From one point of view, the relationship between Revelation and private revelations appears in the relationship between the liturgy and popular piety: The liturgy is the criterion, it is the living form of the Church...fed directly by the Gospel. Popular piety is a sign that the faith is spreading its roots into the heart of a people in such a way that it reaches into daily life. Popular religiosity is the first and fundamental mode of 'inculturation' of the faith. While it must always take its lead and direction from the liturgy, it enriches the faith by involving the heart."