Pope Francis has urged the faithful to not give up on the sacrament of reconciliation, especially those who continue to backslide.

Francis focused on reconciliation, or confession, during his homily Sunday for an annual Mass in St. Peter's Square dedicated to mercy, a signature theme of his papacy.

The pontiff urged the faithful to continue to seek reconciliation because "every time we are forgiven, we are reassured and encouraged."

The divine mercy Sunday celebration was established by Pope John Paul II, and this year kicks off a four-day meeting of Francis' Missionaries of Mercy, formed during the recent Holy Year of Mercy to promote confession.

On Tuesday, the missionaries are due to have an audience with Francis, followed by a special Mass with him at St. Peter's Basilica.