To think of God as a severe judge with whom sinners find no mercy, but of whom they can expect nothing but wrath, is altogether erroneous. This is not the case, though the law teaches nothing else of God. For the law speaks of sinners who do not desire and do not hope for any grace. But those sinners who acknowledge their sins, repent of them, and wish that they had not offended God — who mourn and lament that their lives have been in opposition to God and His commandments, and therefore ask for mercy — shall find mercy, as is here testified. The reason is that God is a merciful God and has a paternal heart. He has pity on us in our misfortune and is moved with compassion, as He declares by the prophet: “Have I any pleasure at all that the wicked should die? saith the Lord God: and not that he should return from his ways, and live?” Therefore when He finds you to be desirous of divine grace, and to hate sin and abandon it, He will cheerfully forgive your debt and show mercy unto you; as we here learn from the servant who acknowledges his debt and asks for mercy.
But as regards the means by which God will be gracious, the Gospel informs us of this in other places; namely, that the Son of God, our dear Lord Jesus Christ, took pity on poor sinners, took their sins upon Himself and paid their penalty by His death. Whoever now trusts in the Lord Jesus and in His death, has gained the good will of God, so that He can neither be angry nor punish. For aside from this He has a heart full of compassion and is moved by our misery. For this reason He of His own accord promised, as soon as Adam and Eve had fallen into sin and death, that the devil should be divested of his power by the seed of the woman. (Luther’s House Postil, Sermon for the Twenty-Second Sunday after Trinity, Volume 3, p. 867)