In the first section of the his pastoral letter, Bishop Donald Kettler talks specifically about the contributions of three popes who helped define mercy as central to Christian life:
“Saint John Paul II makes it the topic of his second encyclical, Dives in Misericordia: On Divine Mercy (1980). He institutionalizes the importance of mercy by establishing the Sunday after Easter as Divine Mercy Sunday and making the first canonization of the new millennium Sister Faustina Kowalska who had a special devotion to divine mercy and a now-famous vision of the outpouring of mercy from Christ. During his last visit to Poland he dedicated the world to divine mercy and called the church to transmit the fire of this mercy to the world. Fittingly, he died on the eve of Divine Mercy Sunday in 2005.
Pope Benedict XVI continued this proclamation of mercy in his first encyclical, Deus Caritas Est: God is Love, in which he makes love, mercy, the center of his social teaching. He returns to this theme in his third encyclical, Caritas in Veritate: Charity in Truth, in which he identifies love or mercy as the normative principle not only for personal relationships such as family or friendships but also for social, economic and political relations. Mercy was also a significant feature of the Second Vatican Council.
The theme of mercy has been central to the papacy of Pope Francis. It is prominent in his preaching, teaching, informal comments in media like Twitter, and in his actions as pope. Things like washing the feet of prisoners, physically embracing those on the margins of society, or sponsoring refugee families witness powerfully to the mercy he calls us to ponder and practice in this Holy Year.”