The proclamation of the kingdom of God
Jesus invites sinners to the table of the kingdom: "I came not to call the righteous, but sinners." He invites them to that conversion without which one cannot enter the kingdom, but shows them in word and deed his Father's boundless mercy for them and the vast "joy in heaven over one sinner who repents". The supreme proof of his love will be the sacrifice of his own life "for the forgiveness of sins".
Source: Catechism of the Catholic Church (Vatican.va)