There is hardly a more sober—if not downright frightening—warning to any professing Christian than that found near the end of Jesus’ teaching on prayer. “For if you forgive others their trespasses, your heavenly Father will also forgive you, but if you do not forgive others their trespasses, neither will your Father forgive your trespasses (Matthew 6:14-15). Here is both a promise and a warning. Jesus promises God’s forgiveness to those who forgive others, while at the same time warns of God’s silent judgment on those who withhold forgiveness.
Forgive just as you have been forgiven. Unanimously, the New Testament raises our forgiveness of those who sin against us to the level of God’s forgiveness of our sins against him. Clearly, God’s forgiveness is now our standard. In fact, there is no other standard for the genuine Christian.
Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you. (Ephesians 4:32)
Put on then, as God’s chosen ones, holy and beloved, compassion, kindness, humility, meekness, and patience, bearing with one another and, if one has a complaint against another, forgiving each other; as the Lord has forgiven you, so you also must forgive. (Colossians 3:12-13)
Whenever we are sinned against, we must choose to remember the extent to which God has released us from our sins through the blood of His Son (Revelation 1:5). In addition, we must bring to mind the wealth of “every spiritual blessing” he has showered upon us in Christ (Ephesians 1:3). This compels us to guard our hearts against a bitter, vengeful spirit, as Peter exhorts,
Finally, all of you, have unity of mind, sympathy, brotherly love, a tender heart, and a humble mind. Do not repay evil for evil or reviling for reviling, but on the contrary, bless, for to this you were called, that you may obtain a blessing. (1 Peter 3:8-9)
Clearly, Jesus is saying that our horizontal forgiveness of other sinners is related to our vertical forgiveness from God. The absence of horizontal forgiveness reveals the absence of vertical forgiveness. This is—and should be—a terrifying thought.