By Fr. Seraphim Michalenko, MIC (Dec 26, 2016)
A definition is the stating of the exact nature — of the necessary inborn character — of a thing; or, it is the "precise meaning" of a word. What is the nature, the inborn character, the meaning of "mercy"?
The Latin word, which is the ultimate root of our English word "mercy," is misericordia. It, in turn, derives from two words: misereri, meaning "to have pity on" or "compassion for" and cor, meaning "heart" (genitive case — cordis: "of the heart"). Mercy, therefore, carries the idea of having compassion on someone with all one's heart. The latter phrase expresses the idea: "From the very inmost depth (or core) of one's being."
The Sacred Scriptures show clearly that mercy is the greatest "relative" characteristic of God, the attribute that extends over all He created (e.g., Ps 145:9); and it explains the whole plan of salvation: the power (virtue) of a compassionate heart that shares another's misery to come to that other's rescue. Saint Thomas, therefore, can fearlessly profess and demonstrate that, with relation to all that exists in creation, mercy is the greatest divine attribute (Summa Th., IIa IIae, 30, 4c).
A "composite" definition of "mercy" (based on definitions found in various dictionaries) would go like this: A feeling of tenderness, aroused by someone's distress or suffering, which inclines (causes) one to spare (abstain from killing/hurting) or to help another who is in one's power and has no claim whatever to (or is completely undeserving of) kindness. Another definition would be: pardon given to someone who could be punished (often used with reference to God when He forgives sin).
Both these definitions make quite understandable what Pope John Paul II expounded in his encyclical on the Mercy of God in Part VII, no. 13, par. 4:
It is precisely because sin exists in the world, which "God so loved ... that He gave His only Son" (Jn 3:16), that God, who "is love" (1 Jn 4:8), cannot reveal Himself otherwise than as mercy.
The essence of mercy is to take into account not only that which is strictly due (as is the case with justice), but also weaknesses, infirmities, and defects of all kinds; and in considering them, to give more than is required by merit and to soften the blow that guilt deservingly brings upon itself through the shutting off, by sin, of the flow of God's goodness. Divine Mercy, therefore, by no means signifies some sort of sentimental emotion (as certain pagan philosophers saw it, branding it "a weakness excusable only in old people and children").
If the Holy Scriptures often refer to "the bowels of mercy" being moved in God (Jer 31:20; Lk 1:78); or if Jesus, for that matter, in His revelations to St. Faustina, uses the biblical expression ("Everything that exists is enclosed in the bowels of My mercy, more deeply than an infant in its mother's womb" from the Diary, 1007), it is not some "gooey" emotion or sentiment that is being brought to our attention. The Hebrew word rahamim carries two meanings: bowels (womb) and mercy. Pope John Paul II explains the various related terms in the lengthy footnote (52) in his encyclical on mercy. What is important, however, is that, from all of them we get a picture of a person tenderly taking care of another even in spite of the latter's possible unworthiness.
Divine Mercy, then appears to be the unchangeable disposition in God by which He cannot "take pleasure in the death of the wicked man, but rather in the wicked man's conversion [turning around back to God] that he may live" (Ezek 33:11).
Father Seraphim Michalenko, MIC, served as vice-postulator in North America for the canonization cause of St. Faustina.