It seems fitting that John Paul II has passed from this life to the next on the eve of the feast of Divine Mercy. He wrote an encylical letter on the mercy of God, and canonized Sister Maria Faustina.
Right from the beginning of my ministry in St. Peter’s See in Rome, I consider this message [of Divine Mercy] my special task. Providence has assigned it to me in the present situation of man, the Church and the world. It could be said that precisely this situation assigned that message to me as my task before God.
— November 22, 1981 at the Shrine of Merciful Love in Collevalenza, Italy
Here’s a short quote from his encylical letter:
The Church proclaims the truth of God’s mercy revealed in the crucified and risen Christ, and she professes it in various ways. Furthermore, she seeks to practice mercy towards people through people, and she sees in this an indispensable condition for solicitude for a better and “more human” world, today and tomorrow. However, at no time and in no historical period-especially at a moment as critical as our own-can the Church forget the prayer that is a cry for the mercy of God amid the many forms of evil which weigh upon humanity and threaten it. Precisely this is the fundamental right and duty of the Church in Christ Jesus, her right and duty towards God and towards humanity. The more the human conscience succumbs to secularization, loses its sense of the very meaning of the word “mercy,” moves away from God and distances itself from the mystery of mercy, the more the Church has the right and the duty to appeal to the God of mercy “with loud cries” (cf. Heb. 5:7). These “loud cries” should be the mark of the Church of our times, cries uttered to God to implore His mercy, the certain manifestation of which she professes and proclaims as having already come in Jesus crucified and risen, that is, in the Paschal Mystery. It is this mystery which bears within itself the most complete revelation of mercy, that is, of that love which is more powerful than death, more powerful than sin and every evil, the love which lifts man up when he falls into the abyss and frees him from the greatest threats.
— Dives in Misericordia (Rich in Mercy), encyclical of Pope John Paul II, 11/30/1980