When Jesus was asked which of the commandments was the greatest, He gave two answers. Notice His response from Matthew 22:37-40:
37And He said to him, "'You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.' 38This is the great and foremost commandment. 39The second is like it, 'You shall love your neighbor as yourself.' 40On these two commandments depend the whole Law and the Prophets."
In His answer, the Lord quoted Deuteronomy 6:5 concerning the love of God and Leviticus 19:18 concerning the love of neighbors. These were the basis of the whole Law of Moses and the Prophets, and they continue today as the basis of God's law in the gospel (Rom. 13:8-9).
These are two separate commandments, but they cannot be kept separately. John explains this in 1John 4:20-21:
20If someone says, "I love God," and hates his brother, he is a liar; for the one who does not love his brother whom he has seen, cannot love God whom he has not seen. 21And this commandment we have from Him, that the one who loves God should love his brother also.
Thus, the love of God and the love of brothers are inextricably combined. We cannot have one without the other. Indeed, our love for God is manifested in our love for one another, and our love for one another is a product of our love for God (1John 4:7).
Consider carefully the implications of this combined sense of our disposition toward God and our brethren. Our attitude toward one directly affects our attitude toward the other. They cannot be separated. Therefore, if we view our brethren with anger, jealousy, bitterness, resentment, malice, or hatred, then we unavoidably damage our relationship with God.
With this in mind, let us consider the passage Jesus quoted concerning the love of neighbors. In Leviticus 19:18, God said to Israel, "You shall not take vengeance, nor bear any grudge against the sons of your people, but you shall love your neighbor as yourself; I am the LORD." Notice that "the sons of your people" and "your neighbor" are references to the same persons, namely, fellow Israelites. This is analogous to the relationships Christians have with one another today. Of course, Jesus elaborated on this in the parable of the good Samaritan and showed that a neighbor is one who acts on the needs of his fellow man (Luke 10:29-37). Also notice that Leviticus 19:18 shows that taking vengeance or bearing a grudge is contrary and incompatible with love. This is a key principle that we must not overlook.
Thus, we see that the love of God and the love of neighbors constrain us to put away thoughts of personal vengeance or grudges. The Scripture admonishes us, saying, "Never take your own revenge, beloved, but leave room for the wrath of God, for it is written, 'Vengeance is mine, I will repay,' says the Lord" (Rom. 12:19). The attitude of this commandment is taken even farther with the many instructions of Scripture that direct us to be forgiving of one another. These instructions leave no place for bearing grudges, but instead they connect our own willingness to forgive others and release our grudges to God's forgiveness toward us. Notice some of these:
Matthew 6:12 -- "And forgive us our debts, as we also have forgiven our debtors."
Mark 11:25-26 -- 25"Whenever you stand praying, forgive, if you have anything against anyone, so that your Father who is in heaven will also forgive you your transgressions. 26But if you do not forgive, neither will your Father who is in heaven forgive your transgressions."
Ephesians 4:32 -- Be kind to one another, tender-hearted, forgiving each other, just as God in Christ also has forgiven you.
Colossians 3:13 -- Bearing with one another, and forgiving each other, whoever has a complaint against anyone; just as the Lord forgave you, so also should you.
Forgiving those who sin against us and releasing grudges against them may seem difficult, but let us consider two examples that leave us without excuse. The first is the Lord Jesus, who appealed to His Father on behalf of His murderers while hanging on the cross, saying, "Father, forgive them; for they do not know what they are doing" (Luke 23:34). The second is Stephen, who like Jesus pleaded for his own murderers as he was dying, saying, "Lord, do not hold this sin against them!" (Acts 7:60). If our dying Savior and His dying servant can forgive their own murderers, hold no grudges, and pray for their enemies, then surely we have no excuse for petty grudges against our brethren.
Therefore, let us give up our grudges, set aside our grievances, and forgive one another. Loving our neighbors as we love ourselves requires this, for we cannot hold against others that which we would not hold against ourselves. Moreover, loving God requires this, for we cannot love God unless we love one another. The connection goes even farther, for if we would have God to forgive us and set aside His grievances, then we must do the same toward our brethren. If we if abide by these things, then we are well on our way to keeping the foremost commandments of God's law.
