The Grace Reading
Read plainly, this is a trade. Forgiveness for forgiveness, measure for measure. If that unsettles you, it should. Jesus meant it to.
Look at where the words sit. This is the Sermon on the Mount, spoken to people under the Law, before the cross. Throughout the sermon Jesus takes the Law and turns up the voltage: anger becomes murder, a glance becomes adultery, and the standard lands at “Therefore you shall be perfect, just as your Father in heaven is perfect” (Matthew 5:48). He is not lowering the bar for sincere people. He is raising it beyond reach, because the Law was given to silence every claim of self-righteousness and lead us to Christ (Galatians 3:24).
Matthew 6:14–15 is the Law's arithmetic applied to forgiveness: you will receive exactly what you give. Perfectly fair, and perfectly hopeless. Nobody forgives flawlessly enough to earn the forgiveness of God on those terms. That is the point. The sermon is meant to empty your hands.
Then comes the cross, and the arithmetic is reversed. “And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you” (Ephesians 4:32). Notice the order, and notice the tense. Forgave. Past tense, finished. Colossians 3:13 says it the same way: “even as Christ forgave you, so you also must do.” After the cross, your forgiveness of others flows from God's forgiveness of you. It never flows toward it.
You do not forgive in order to be forgiven. You forgive because you already are. That is not a loophole. That is the difference between two covenants.
The Common Misreading
This verse is regularly preached as a standing threat over believers: hold a grudge, and God holds your sins. Some carry a quiet dread for years that a person they have not fully forgiven will cost them heaven. That reading turns forgiveness into a wage and keeps the very fear the cross was meant to end.
None of this makes bitterness harmless. Unforgiveness is a poison, and grace does not excuse it. Grace dissolves it. The person who knows how much they have been forgiven becomes the kind of person who forgives (Luke 7:47). God is not withholding your pardon until you perform. He is pointing at your pardon and inviting you to give away what you have already received.