There is much sloppy thought and practice in regards to the biblical doctrine of forgiveness. One of the most common errors in the church and outside of it is not the withholding of forgiveness, but the idea that all of us are required to forgive everyone, all the time, for everything. If that were the case, both the Scriptures and this sermon series would be very short. The verse and this sermon series would say: "forgive everyone, all the time, for everything." - period. But, the Bible doesn't and thus, I don't. The messy part is figuring out the biblical principles and parameters and applying those to the messy realities of life. In all areas of life, it is easy to overemphasize one thing or another and this is particularly so with the doctrine of forgiveness.
Disclaimers: 1) There is no way that I can speak to all of the aspects in one, two, or even three sermons. This is going to take a while. 2) I also cannot answer all the questions in one sermon. 3) Please be patient. 4) It may be a while before I define forgiveness. Definitions are important, but I must lay some groundwork first. Now, let's look at some important basic principles.
In verse 12, we read of the plea for forgiveness. There is an assumption that all of us need forgiveness. There is no conditional phrase – it is a petition. We are making a plea for God's grace and we need forgiveness because we have debts. Sin is pictured here as a debt, and the sinner as a debtor. All humankind has a debt to the Creator. A debt of obedience to His Word and love of His person and works. It is a debt which is a natural part of our relationship to Him as the creature. And that debt is not paid! We often think we do, but no one pays what is owed. This ought to prompt a question: If our sins are all forgiven in Christ, why should we continue to ask forgiveness? Among the answers are: 1) Because we sin daily, 2) Because such prayer is a chief part of thankfulness, and 3) Because in this way we are strengthened, kept humble and meek, and are taught mercy and grace to our fellow man. Notice also that there is an assumption that all of us have been sinned against. But we have to remember that the assumption works both ways. If it is assured that we are sinned against, is it not also assured that we offend? Is it not assured that the offense is real? Is it not also assured that we would long to be restored and forgiven? In this verse, the plea for God's grace is intimately related to our relationship to our neighbor. So the first BIG fundamental of forgiveness is, forgiveness is theocentric. The concept and practice of the biblical doctrine of forgiveness is based upon who God is. God is Merciful; God is; Just; God is Ready to Forgive. The concept and practice of the biblical doctrine of forgiveness is also based upon what God does. He truly forgives those who come to Him seeking forgiveness; He truly forgives those who come to Him even if they struggle and offend more than once; He also withholds forgiveness from some, (but this will be dealt with in a subsequent ministry). This principle is no small matter. The importance of the biblical doctrine of forgiveness is found in the latter half of verse 12. The use of the word AS indicates, "in that manner". Please get this. The grace you seek is the grace you are obligated to extend. When understood as a greater/lesser argument, the force comes into focus. We are asking much, much more of God than anyone can ever ask of us.
In verse 14 we read of the promise of forgiveness. Now we see a conditional (it will not be the last). How important is it that that you forgive? The if/then clause in this verse is quite stark: you cannot have one without the other. We are going to be confronted with absolutes which will cause us some discomfort as we see the biblical doctrine, but consider your own sins and forgiveness. Your sins are paid for with the broken body and shed blood of Christ. It was absolutely necessary that His blood be shed so that you may live. That sacrifice on your behalf was graciously applied to you and you rejoice in it and you praise His name for it. How can you be miserly with forgiveness when it was so graciously applied to you? In this we can see that the grant of divine forgiveness places obligations on the recipient. If you claim the merits of the blood of Christ, you also claim the obligations of the covenant. If you claim the merits of the blood of Christ, you also claim that you have no claim apart from the Lord's mercy. If you claim the merits of the blood of Christ, you claim that you are unable to meet the demands of the debt you owe. You are, therefore, in no position to withhold forgiveness. Indeed, it is an extreme act of despising the sacrifice of Christ to withhold forgiveness. It is also an underestimation of the significance of the depths of your own sins. This is why the link between your willingness to forgive and the action of divine forgiveness is so strong.
Lastly, in verse 15 we read that there is a prerequisite of forgiveness. "But if you forgive not men their trespasses…." The principle already implied is now stated explicitly. We cannot expect divine forgiveness if we withhold it from others. Your readiness to forgive (or lack of readiness) is very strong indication of your appreciation for divine forgiveness and is even a prerequisite for it! How can you expect pardon from God when you withhold it? To blithely refuse to forgive your fellow man is to flirt with divine condemnation toward yourself. That potential should prompt every true believer to sober examination and reflection.
So, in summary, you are to forgive you fellow man because: 1) God commands that you forgive. You do not have the prerogative to withhold it. 2) The Lord has forgiven you [the assumption is that the reader is a true believer]. 3) Forgiveness is withheld by the Lord if you withhold it. 4) You are not to avenge yourself, but to leave that to God. He will execute His justice in His time. No amateur Providence allowed! In forgiving because you have been forgiven, you will be strengthened in your walk, you will bring glory to God, and you will experience peace in your mind and with your fellow man.