God's law is comprehensive in its scope, giving us principles that we can apply to any situation in our lives. Jesus Himself tells us as much in His exposition of God's law in the Sermon on the Mount. His interpretation of the sixth commandment, for example, reveals that this statute is given not just to deal with murderers but with every episode of unjust anger, every malicious insult, and other actions of the heart and tongue that might give birth to murder (Matt. 5:21–22).
Our Savior's application of the law of God shows us how the commandments also mandate the opposite of what they forbid and forbid the opposite of what they mandate. In His discussion of the sixth commandment, Jesus says that this rule directs us to seek forgiveness and reconciliation whenever possible (vv. 23–26). Thus, the Heidelberg Catechism is surely right to find the duties of peacemaking, gentleness, mercy, and patience in our Creator's prohibition of murder (Q&A 107).
Of course, the Bible often emphasizes forgiveness and mercy. We read positive examples of long-suffering and forgiveness in Joseph (Gen. 45) and the prodigal son's father (Luke 15:11–32). We also learn that God is eager to forgive His people when they return to Him (Deut. 30:1–3; Ps. 130; Luke 7:36–50). Jesus even warns us that our sins are not forgiven if we refuse to pardon others (Matt. 6:14–15).
In all of these cases, repentance is the prerequisite of forgiveness and reconciliation. The Lord does not forgive us if we do not repent and trust in Jesus, as the prerequisite for restoring the relationship is to acknowledge that we have broken it by our sin and that we are sorry for what we have done. But this is true on a human level as well. Although God tells us to be patient with the faults of others, He does not command us to forgive people who show no sign of repentance for what they have done to us and others. We may forgive such people, but we are not required to do so, although we must take care that the root of bitterness does not become established in our hearts when we are not reconciled to others (Heb. 12:15).
When people express true sorrow for what they have done and ask for our pardon, however, we cannot do otherwise than to forgive them. Since the Lord has forgiven us, we too must forgive (Col. 3:12–14).
The forgiveness we enjoy from God in Christ Jesus has consequences for our lives. First, we are absolved from guilt and never need to fear His wrath again. Furthermore, God’s forgiveness means that we, too, must forgive those who have sinned against us when they express sorrow for what they have done. We are not allowed to hold grudges against others, but we must embrace other believers as brothers and sisters when they ask for our forgiveness.