Christ, then, reveals God who is Father, who is “love,” as St. John will express it in his first letter; Christ reveals God as “rich in mercy,” as we read in St. Paul. This truth is not just the subject of a teaching; it is a reality made present to us by Christ. Making the Father present as love and mercy is, in Christ’s own consciousness, the fundamental touchstone of His mission as the Messiah; this is confirmed by the words that He uttered first in the synagogue at Nazareth and later in the presence of His disciples and of John the Baptist’s messengers.
On the basis of this way of manifesting the presence of God who is Father, love and mercy, Jesus makes mercy one of the principal themes of His preaching. As is His custom, He first teaches “in parables,” since these express better the very essence of things. It is sufficient to recall the parable of the prodigal son, or the parable of the Good Samaritan, but also – by contrast – the parable of the merciless servant. There are many passages in the teaching of Christ that manifest love-mercy under some ever-fresh aspect. We need only consider the Good Shepherd who goes in search of the lost sheep, or the woman who sweeps the house in search of the lost coin. The Gospel writer who particularly treats of these themes in Christ’s teaching is Luke, whose Gospel has earned the title of “the Gospel of mercy.”
When one speaks of preaching, one encounters a problem of major importance with reference to the meaning of terms and the content of concepts, especially the content of the concept of “mercy” (in relationship to the concept of “love”). A grasp of the content of these concepts is the key to understanding the very reality of mercy. And this is what is most important for us. However, before devoting a further part of our considerations to this subject, that is to say, to establishing the meaning of the vocabulary and the content proper to the concept of mercy,” we must note that Christ, in revealing the love – mercy of God, at the same time demanded from people that they also should be guided in their lives by love and mercy. This requirement forms part of the very essence of the messianic message, and constitutes the heart of the Gospel ethos. The Teacher expresses this both through the medium of the commandment which He describes as “the greatest,” and also in the form of a blessing, when in the Sermon on the Mount He proclaims: “Blessed are the merciful, for they shall obtain mercy.” – from Dives in Misericordia, 1980