Blessed are the merciful, for they shall receive mercy. (5:7)
The first four beatitudes deal entirely with inner principles, principles of the heart and mind. They are concerned with the way we see ourselves before God. The last four are outward manifestations of those attitudes. Those who in poverty of spirit recognize their need of mercy are led to show mercy to others (v. 7). Those who mourn over their sin are led to purity of heart (v. 8). Those who are meek always seek to make peace (v. 9). And those who hunger and thirst for righteousness are never unwilling to pay the price of being persecuted for righteousness’ sake (v. 10).
The concept of mercy is seen throughout Scripture, from the Fall to the consummation of history at the return of Christ. Mercy is a desperately needed gift of God’s providential and redemptive work on behalf of sinners—and the Lord requires His people to follow His example by extending mercy to others.
To discover its essence we will look at three basic aspects of mercy: its meaning, its source, and its practice.
The Meaning of Mercy
For the most part, the days in which Jesus lived and taught were not characterized by mercy. The Jewish religionists themselves were not inclined to show mercy, because mercy is not characteristic of those who are proud, self-righteous, and judgmental. To many—perhaps most—of Jesus’ hearers, showing mercy was considered one of the least of virtues, if it was thought to be a virtue at all. It was in the same category as love—reserved for those who had shown the virtue to you. You loved those who loved you, and you showed mercy to those who showed mercy to you. That attitude was condemned by Jesus later in the Sermon on the Mount. “You have heard that it was said, ‘You shall love your neighbor, and hate your enemy'” (Matt. 5:43). But such a shallow selfish kind of love that even the outcast tax-gatherers practiced (v. 46) was not acceptable to the Savior. He said, “Love your enemies, and pray for those who persecute you in order that you may be sons of your Father who is in heaven…. For if you love those who love you, what reward have you?… And if you greet your brothers only, what do you do more than others? Do not even the Gentiles do the same?” (vv. 44-47).
Yet many people have interpreted this beatitude in another way that is just as selfish and humanistic: they maintain that our being merciful causes those around us, especially those to whom we show mercy, to be merciful to us. Mercy given will mean mercy received. For such people, mercy is shown to others purely in an effort toward self-seeking.
The ancient rabbi Gamaliel is quoted in the Talmud as saying, “Whenever thou hast mercy, God will have mercy upon thee, and if thou hast not mercy, neither will God have mercy on thee.” Gamaliel’s idea is right. When God is involved there will be mercy for mercy. “If you forgive men for their transgressions,” Jesus said, “your heavenly Father will also forgive you. But if you do not forgive men, then your Father will not forgive your transgressions” (Matt. 6:14-15).
But as a platitude applied among men, the principle does not work. One writer sentimentally says, “This is the great truth of life: if people see us care, they will care.” Yet neither Scripture nor experience bears out that idea. God works that way, but the world does not. With God there is always proper reciprocation, and with interest. If we honor God, He will honor us; if we show mercy to others, especially to His children, He will show even more abundant mercy to us. But that is not the world’s way.
A popular Roman philosopher called mercy “the disease of the soul.” It was the supreme sign of weakness. Mercy was a sign that you did not have what it takes to be a real man and especially a real Roman. The Romans glorified manly courage, strict justice, firm discipline, and, above all, absolute power. They looked down on mercy, because mercy to them was weakness, and weakness was despised above all other human limitations.
During much of Roman history, a father had the right of patria opitestas, of deciding whether or not his newborn child would live or die. As the infant was held up for him to see, the father would turn his thumb up if he wanted the child to live, down if he wanted it to die. If his thumb turned down the child was immediately drowned. Citizens had the same life-or-death power over slaves. At any time and for any reason they could kill and bury a slave, with no fear of arrest or reprisal. Husbands could even have their wives put to death on the least provocation. Today abortion reflects the same merciless attitude. A society that despises mercy is a society that glorifies brutality.
The underlying motive of self-concern has characterized men in general and societies in general since the Fall. We see it expressed today in such sayings as, “If you don’t look out for yourself, no one else will.” Such popular proverbs are generally true, because they reflect the basic selfish nature of fallen man. Men are not naturally inclined to repay mercy for mercy.
The best illustration of that fact is the Lord Himself. Jesus Christ was the most merciful human being who ever lived. He reached out to heal the sick, restore the crippled, give sight to the blind, hearing to the deaf, and even life to the dead. He found prostitutes, tax collectors, the debauched and the drunken, and drew them into His circle of love and forgiveness. When the scribes and Pharisees brought the adulteress to Him to see if He would agree to her stoning, He confronted them with their merciless hypocrisy: “He who is without sin among you, let him be the first to throw a stone at her.” When no one stepped forward to condemn her, Jesus said to her, “Neither do I condemn you; go your way. From now on sin no more” (John 8:7-11). Jesus wept with the sorrowing and gave companionship to the lonely. He took little children into His arms and blessed them. He was merciful to everyone. He was mercy incarnate, just as He was love incarnate.
Yet what was the response to Jesus’ mercy? He shamed the woman’s accusers into inaction, but they did not become merciful. By the time the accounts of John 8 ended, Jesus’ opponents “picked up stones to throw at Him” (v. 59). When the scribes and Pharisees saw Jesus “eating with the sinners and tax-gatherers,” they asked His disciples why their Master associated with such unworthy people (Mark 2:16).
The more Jesus showed mercy, the more He showed up the unmercifulness of the Jewish religious leaders. The more He showed mercy, the more they were determined to put Him out of the way. The ultimate outcome of His mercy was the cross. In Jesus’ crucifixion, two merciless systems—merciless government and merciless religion—united to kill Him. Totalitarian Rome joined intolerant Judaism to destroy the Prince of mercy.
The fifth beatitude does not teach that mercy to men brings mercy from men, but that mercy to men brings mercy from God. If we are merciful to others, God will be merciful to us, whether men are or not. God is the subject of the second clause, just as in the other beatitudes. It is God who gives the kingdom of heaven to the poor in spirit, comfort to those who mourn, the earth to the meek, and satisfaction to those who hunger and thirst for righteousness. Those who are merciful… shall receive mercy from God. God gives the divine blessings to those who obey His divine standards.
Merciful is from eleēmōn, from which we also get eleemosynary, meaning beneficial or charitable. Hebrews 2:17 speaks of Jesus as our “merciful and faithful high priest.” Christ is the supreme example of mercy and the supreme dispenser of mercy. It is from Jesus Christ that both redeeming and sustaining mercy come.
In the Septuagint (the Greek Old Testament) the same term is used to translate the Hebrew ḥesed, one of the most commonly used words to describe God’s character. It is usually translated as mercy, love, lovingkindness, or steadfast love (Ps. 17:7; 51:1; Isa. 63:7; Jer. 9:24; etc.). The basic meaning is to give help to the afflicted and to rescue the helpless. It is compassion in action.
Jesus is not speaking of detached or powerless sentiment that is unwilling or unable to help those for whom there is sympathy. Nor is He speaking of the false mercy, the feigned pity, that gives help only to salve a guilty conscience or to impress others with its appearance of virtue. And it is not passive, silent concern which, though genuine, is unable to give tangible help. It is genuine compassion expressed in genuine help, selfless concern expressed in selfless deeds.
Jesus says in effect, “The people in My kingdom are not takers but givers, not pretending helpers but practical helpers. They are not condemners but mercy givers.” The selfish, self-satisfied, and self-righteous do not bother to help anyone—unless they think something is in it for them. Sometimes they even justify their lack of love and mercy under the guise of religious duty. Once when the Pharisees and scribes questioned why His disciples did not observe the traditions of the elders, Jesus replied, “Moses said, ‘Honor your father and your mother’; and ‘He who speaks evil of father or mother, let him be put to death’; but you say, ‘If a man says to his father or his mother, anything of mine you might have been helped by is Corban (that is to say, given to God),’ you no longer permit him to do anything for his father or his mother; thus invalidating the word of God by your tradition which you have handed down” (Mark 7:10-13). In the name of hypocritical religious tradition, compassion toward parents in such a case was actually forbidden.
Mercy is meeting people’s needs. It is not simply feeling compassion but showing compassion, not only sympathizing but giving a helping hand. Mercy is giving food to the hungry, comfort to the bereaved, love to the rejected, forgiveness to the offender, companionship to the lonely. It is therefore one of the loveliest and noblest of all virtues.
In Shakespeare’s The Merchant of Venice (4.1.180-85) Portia says,
The quality of mercy is not strain’d;
It droppeth, as the gentle rain from heaven,
Upon the place beneath: it is twice bless’d.
It blesseth him that gives, and him that takes:
‘Tis mightiest in the mightiest; it becomes
The throned monarch better than his crown:
Mercy and Forgiveness
A clearer understanding of mercy can be gained by working through some comparisons. Mercy has much in common with forgiveness but is distinct from it. Paul tells us that Jesus “saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit” (Titus 3:5). God’s forgiveness of our sins flows from His mercy. But mercy is bigger than forgiveness, because God is merciful to us even when we do not sin, just as we can be merciful to those who have never done anything against us. God’s mercy does not just forgive our transgressions, but reaches to all our weakness and need.
“The Lord’s lovingkindnesses [mercies, kjv] indeed never cease, for His compassions never fail. They are new every morning; great is Thy faithfulness” (Lam. 3:22). God’s mercy to His children never ceases.
Mercy and Love
Forgiveness flows out of mercy, and mercy flows out of love. “But God, being rich in mercy, because of His great love with which He loved us, even when we were dead in our transgressions, made us alive together with Christ” (Eph. 2:4-5). Just as mercy is more than forgiveness, love is more than mercy. Love manifests itself in many ways that do not involve either forgiveness or mercy. Love loves even when there is no wrong to forgive or need to meet. The Father loves the Son and the Son loves the Father, although they both are without sin and without need. They both love the holy angels, although the angels are without sin and need. When we enter heaven we, too, will be without sin or need, yet God’s love for us will, in comparison to eternity, only be just beginning.
Mercy is the physician; love is the friend. Mercy acts because of need; love acts because of affection, whether there is need or not. Mercy is reserved for times of trouble; love is constant. There can be no true mercy apart from love, but there can be true love apart from mercy.
Mercy and Grace
Mercy is also related to grace, which flows out of love just as forgiveness flows out of mercy. In each of his three pastoral epistles Paul includes the words “grace, mercy and peace” in his salutations (1 Tim. 1:2; 2 Tim. 1:2; Titus 1:4, kjv). Grace and mercy have the closest possible relationship; yet they are different. Mercy and its related terms all have to do with pain, misery, and distress—with the consequences of sin. Whether because of our individual sins or because of the sinful world in which we live, all of our problems, in the last analysis, are sin problems. It is with those problems that mercy gives help. Grace, on the other hand, deals with sin itself. Mercy deals with the symptoms, grace with the cause. Mercy offers relief from punishment; grace offers pardon for the crime. Mercy eliminates the pain; grace cures the disease.
When the good Samaritan bound up the wounds of the man who had been beaten and robbed, he showed mercy. When he took him to the nearest inn and paid for his lodging until he was well, he showed grace. His mercy relieved the pain; his grace provided for healing.
Mercy relates to the negative; grace relates to the positive. In relation to salvation, mercy says, “No hell,” whereas grace says, “Heaven.” Mercy says, “I pity you”; grace says, “I pardon you.”
Mercy and Justice
Mercy is also related to justice, although, on the surface, they seem to be incompatible. Justice gives exactly what is deserved; whereas mercy gives less punishment and more help than is deserved. It is difficult, therefore, for some people to understand how God can be both just and merciful at the same time to the same person. If God is completely just, how could He ever not punish sin totally? For Him to be merciful would seem to negate His justice. The truth is that God does not show mercy without punishing sin; and for Him to offer mercy without punishment would negate His justice.
Mercy that ignores sin is false mercy and is no more merciful than it is just. It is that sort of false mercy that Saul showed to King Agag after God had clearly instructed Saul to kill every Amalekite (1 Sam. 15:3, 9). It is that sort of false mercy that David showed to his rebellious and wicked son Absalom when he was young. Because David did not deal with Absalom’s sin, his attitude toward his son was unrighteous sentimentality, neither justice nor mercy—and it served to confirm Absalom in his wickedness.
That sort of false mercy is common in our day. It is thought to be unloving and unkind to hold people responsible for their sins. But that is a cheap grace that is not just and is not merciful, that offers neither punishment nor pardon for sin. And because it merely overlooks sin, it leaves sin; and the one who relies on that sort of mercy is left in his sin. To cancel justice is to cancel mercy. To ignore sin is to deny the truth; and mercy and truth are inseparable, they “are met together” (Ps. 85:10, kjv). In every true act of mercy, someone pays the price. God did, the Good Samaritan did, and so do we. To be merciful is to bear the load for someone else.
To expect to enter the sphere of God’s mercy without repenting from our sin is but wishful thinking. And for the church to offer hope of God’s mercy apart from repentance from sin is to offer false hope through a false gospel. God offers nothing but merciless judgment to those who will not turn from their sin to the Savior. Neither relying on good works nor relying on God’s overlooking sin will bring salvation. Neither trusting in personal goodness nor presuming on God’s goodness will bring entrance into the kingdom. Those who do not come to God on His terms have no claim on His mercy.
God’s mercy is grounded not only in His love but in His justice. It is not grounded in sentiment but in Christ’s atoning blood, which paid the penalty for and cleanses from sin those who believe in Him. Without being punished and removed, even the least of our sin would eternally separate us from God.
The good news of the gospel is that Christ paid the penalty for all sins in order that God might be merciful to all sinners. On the cross Jesus satisfied God’s justice, and when a person trusts in that satisfying sacrifice God opens the floodgates of His mercy. The good news of the gospel is not that God winked at justice, glossed over sin, and compromised righteousness. The good news is that in the shedding of Christ’s blood justice was satisfied, sin was forgiven, righteousness was fulfilled, and mercy was made available. There is never an excuse for sin, but always a remedy.
Mercy, therefore, is more than forgiveness and less than love. It is different from grace and is one with justice. And what is true of God’s mercy should be true of ours.
Mercy led Abraham to rescue his selfish nephew Lot from Chedorlaomer and his allies. Mercy led Joseph to forgive his brothers and to provide them food for their families. Mercy led Moses to plead with the Lord to remove the leprosy with which his sister Miriam had been punished. Mercy led David to spare the life of Saul.
Those who are unmerciful will not receive mercy from God. In one of his imprecatory psalms David says of an unnamed wicked man, “Let the iniquity of his fathers be remembered before the Lord, and do not let the sin of his mother be blotted out. Let them be before the Lord continually, that He may cut off their memory from the earth.” David’s anger was not vengeful or retaliatory. That man and his family did not deserve mercy because they were not themselves merciful. “He did not remember to show lovingkindness, but persecuted the afflicted and needy man, and the despondent in heart, to put them to death” (Ps. 109:14-16).
Paul characterizes godless men as unrighteous, wicked, greedy, evil, envious, murderous, deceitful, malicious, gossiping, slanderous, haters of God, insolent, arrogant, boastful, disobedient to parents, without understanding, untrustworthy, and unloving. The climaxing evil of that long list, however, is being unmerciful (Rom. 1:29-31). Mercilessness is the capstone marking those who reject God’s mercy.
“The merciful man does himself good, but the cruel man does himself harm” (Prov. 11:17). The way to happiness is through mercy; the way to misery is through cruelty. The truly merciful person is even kind to animals, whereas the merciless person is cruel to everything. “A righteous man has regard for the life of his beast, but the compassion of the wicked is cruel” (Prov. 12:10).
In His Olivet discourse Jesus warned that those who claim to belong to Him but who have not served and shown compassion on the hungry, the thirsty, the stranger, the naked, the sick, and the imprisoned will not be allowed to enter His kingdom. He will say to them, “Depart from Me, accursed ones, into the eternal fire which has been prepared for the devil and his angels; for I was hungry, and you gave Me nothing to eat; I was thirsty, and you gave Me nothing to drink; I was a stranger, and you did not invite Me in; naked, and you did not clothe Me; sick, and in prison, and you did not visit Me.” When they say, ‘”Lord, when did we see You hungry,… He will answer them, saying, ‘Truly I say to you, to the extent that you did not do it to one of the least of these, you did not do it to Me'” (Matt. 25:41-45).
James writes, “Whoever keeps the whole law and yet stumbles in one point, he has become guilty of all. For He who said, ‘Do not commit adultery,’ also said, ‘Do not commit murder.’ Now if you do not commit adultery, but do commit murder, you have become a transgressor of the law. So speak and so act, as those who are to be judged by the law of liberty. For judgment will be merciless to one who has shown no mercy” (James 2:10-13a).
In the midst of our corrupt, ego-centered, and selfish society that tells us to grab everything we can get, the voice of God tells us to give everything we can give. The true character of mercy is in giving—giving compassion, giving help, giving time, giving forgiveness, giving money, giving ourselves. The children of the King are merciful. Those who are merciless face judgment; but “mercy triumphs over judgment” (James 2:13b).
The Source of Mercy
Pure mercy is a gift of God. It is not a natural attribute of man but is a gift that comes with the new birth. We can be merciful in its full sense and with a righteous motive only when we have experienced God’s mercy. Mercy is only for those who through grace and divine power have met the requirements of the first four beatitudes. It is only for those who by the work of the Holy Spirit bow humbly before God in poverty of spirit, who mourn over and turn from their sin, who are meek and submissive to His control, and who hunger and thirst above all else for His righteousness. The way of mercy is the way of humility, repentance, surrender, and holiness.
Balaam continually prostituted his ministry; trying to keep within the letter of God’s will while conspiring with a pagan king against God’s people. He presumptuously prayed, “Let me die the death of the upright, and let my end be like his!” (Num. 23:10). As one Puritan commentator observed, Balaam wanted to die like the righteous, but he did not want to live like the righteous. Many people want God’s mercy but not on God’s terms.
God has both absolute and relative attributes. His absolute attributes—such as love, truth, and holiness—have characterized Him from all eternity. They were characteristic of Him before He created angels, or the world, or man. But His relative attributes—such as mercy, justice, and grace—were not expressed until His creatures came into being. In fact they were not manifest until man, the creature made in His own image, sinned and became separated from his Creator. Apart from sin and evil, mercy, justice, and grace have no meaning.
When man fell, God’s love was extended to His fallen creatures in mercy. And only when they receive His mercy can they reflect His mercy. God is the source of mercy. “For as high as the heavens are above the earth, so great is His lovingkindness [mercy] toward those who fear Him” (Ps. 103:11). It is because we have the resource of God’s mercy that Jesus commanded, “Be merciful, just as your Father is merciful” (Luke 6:36).
Donald Barnhouse writes,
When Jesus Christ died on the cross, all the work of God for man’s salvation passed out of the realm of prophecy and became historical fact. God has now had mercy upon us. For anyone to pray, “God have mercy on me” is the equivalent of asking Him to repeat the sacrifice of Christ. All the mercy that God ever will have on man He has already had, when Christ died. That is the totality of mercy. There could not be any more…. The fountain is now opened, and it is flowing, and it continues to flow freely. (Romans [Grand Rapids: Eerdmans, 1983], 4:4)
We cannot have the blessing apart from the Blesser. We cannot even meet the condition apart from the One who has set the condition. We are blessed by God when we are merciful to others, and we are able to be merciful to others because we have already received salvation’s mercy. And when we share the mercy received, we shall receive mercy even beyond what we already have.
We never sing more truthfully than when we sing, “Mercy there was great and grace was free; pardon there was multiplied to me; there my burdened soul found liberty, at Calvary.”
The Practice of Mercy
The most obvious way we can show mercy is through physical acts, as did the good Samaritan. As Jesus specifically commands, we are to feed the hungry, clothe the naked, visit the sick and imprisoned, and give any other practical help that is needed. In serving others in need, we demonstrate a heart of mercy.
It is helpful to note that the way of mercy did not begin with the New Testament. God has always intended for mercy to characterize His people. The Old Testament law taught, “You shall not harden your heart, nor close your hand from your poor brother; but you shall freely open your hand to him, and shall generously lend him sufficient for his need in whatever he lacks” (Deut. 15:7-8). Even in the year of release, when all debts were canceled, Israelites were to give their poor countrymen whatever they needed. They were warned, “Beware, lest there is a base thought in your heart, saying ‘The seventh year, the year of remission, is near,’ and your eye is hostile toward your poor brother, and you give him nothing” (v. 9).
Mercy is also to be shown in our attitudes. Mercy does not hold a grudge, harbor resentment, capitalize on another’s failure or weakness, or publicize another’s sin. On a great table at which he fed countless hundreds of people, Augustine inscribed,
Whoever thinks that he is able,
To nibble at the life of absent friends,
Must know that he’s unworthy of this table.
The vindictive, heartless, indifferent are not subjects of Christ’s kingdom. When they pass need by on the other side, as the priest and the Levite did in the story of the good Samaritan, they show they have passed Christ by.
Mercy is also to be shown spiritually. First, it is shown through pity. Augustine said, “If I weep for the body from which the soul is departed, should I not weep for the soul from which God is departed?” The sensitive Christian will grieve more for lost souls than for lost bodies. Because we have experienced God’s mercy, we are to have great concern for those who have not.
Jesus’ last words from the cross were words of mercy. For His executioners He prayed, “Father, forgive them; for they do not know what they are doing” (Luke 23:34). To the penitent thief hanging beside Him He said, “Truly I say to you, today you shall be with Me in Paradise” (v. 43). To His mother He said, ‘”Woman, behold your son!’ Then He said to the disciple [John], ‘Behold, your mother!’ And from that hour the disciple took her into his own household” (John 19:26-27). Like his Master, Stephen prayed for those who were taking his life, “Lord, do not hold this sin against them!” (Acts 7:60).
Second, we are to show spiritual mercy by confrontation. Paul says that, as Christ’s servants, we should gently correct “those who are in opposition, if perhaps God may grant them repentance leading to the knowledge of the truth” (2 Tim. 2:25). We are to be willing to confront others about their sin in order that they might come to God for salvation. When certain teachers were “upsetting whole families, teaching things they should not teach, for the sake of sordid gain,” Paul told Titus to “reprove them severely that they may be sound in the faith” (Titus 1:11, 13). Love and mercy will be severe when that is necessary for the sake of an erring brother and for the sake of Christ’s church. In such cases it is cruel to say nothing and let the harm continue.
As Jude closed his letter with the encouragement to “keep yourselves in the love of God, waiting anxiously for the mercy of our Lord Jesus Christ to eternal life,” he also admonished, “And have mercy on some, who are doubting; save others, snatching them out of the fire; and on some have mercy with fear, hating even the garment polluted by the flesh” (Jude 21-23). Extreme situations require extreme care, but we are to show mercy even to those trapped in the worst systems of apostasy
Third, we are to show spiritual mercy by praying. The sacrifice of prayer for those without God is an act of mercy. Our mercy can be measured by our prayer for the unsaved and for Christians who are walking in disobedience.
Fourth, we are to show spiritual mercy by proclaiming the saving gospel of Jesus Christ—the most merciful thing we can do.
The Result of Mercy
Reflecting on the fact that when we are merciful we receive mercy, we see God’s cycle of mercy. God is merciful to us by saving us through Christ; in obedience we are merciful to others; and God in faithfulness gives us even more mercy, pouring out blessing for our needs and withholding severe chastening for our sin.
As in the other beatitudes, the emphatic pronoun autos (they) indicates that only those who are merciful qualify to receive mercy David sang of the Lord, “With the kind Thou dost show Thyself kind” (2 Sam. 22:26). Speaking of the opposite side of the same truth, James says, “For judgment will be merciless to one who has shown no mercy” (James 2:13). At the end of the disciples’ prayer Jesus explained, “For if you forgive men for their transgressions, your heavenly Father will also forgive you. But if you do not forgive men, then your Father will not forgive your transgressions” (Matt. 6:14-15). Again the emphatic truth is that God will respond with chastening for an unforgiving disciple.
Neither in that passage nor in this beatitude is Jesus speaking of our mercy gaining us salvation. We do not earn salvation by being merciful. We must be saved by God’s mercy before we can truly be merciful. We cannot work our way into heaven even by a lifetime of merciful deeds, any more than by good works of any sort. God does not give mercy for merit; He gives mercy in grace, because it is needed, not because it is earned.
To illustrate the working of God’s mercy Jesus told the parable of a slave who had been graciously forgiven a great debt by the king. The man then went to a fellow slave who owed him a pittance by comparison and demanded that every cent be repaid and had him thrown into prison. When the king heard of the incident, he called the first man to him and said, ‘”You wicked slave, I forgave you all that debt because you entreated me. Should you not also have had mercy on your fellow slave, even as I had mercy on you?’ And his lord, moved with anger, handed him over to the torturers until he should repay all that was owed him. So shall My heavenly Father also do to you, if each of you does not forgive his brother from your heart” (Matt. 18:23-35).
In that parable Jesus gives a picture of God’s saving mercy in relation to forgiving others (vv. 21-22). The first man pleaded with God for mercy and received it. The fact that he, in turn, was unmerciful was so inconsistent with his own salvation that he was chastened until he repented. The Lord will chasten, if need be, to produce repentance in a stubborn child. Mercy to others is a mark of salvation. When we do not show it, we may be disciplined until we do. When we hold back mercy, God restricts His flow of mercy to us, and we forfeit blessing. The presence of chastening and the absence of blessing attend an unmerciful believer.
If we have received from a holy God unlimited mercy that cancels our unpayable debt of sin—we who had no righteousness but were poor in spirit, mourning over our load of sin in beggarly, helpless condition, wretched and doomed, meek before almighty God, hungry and thirsty for a righteousness we did not have and could not attain—it surely follows that we should be merciful to others.
Source: MacArthur New Testament Commentary, Matthew 1-7.