Why all the fuss over forgiveness?

John MacArthur, in his introduction to Philemon:

You ask yourself the question: of all of the subjects that Paul could have written about, why in the world did he pick the subject of forgiveness? This is this just this little isolated kind of odd, out of sync, obtuse tangential little letter stuck in the middle of these great sweeping epistles to talk to one guy about forgiving one slave. Why all this fuss? Again I say, because never is a believer more like God, more like Christ than when He or she forgives because that’s the nature of God and the nature of Christ which is most wonderfully applied to us in salvation. We read throughout the New Testament, don’t we, be like Christ, be like Christ, walk like He walked, remember Jesus Christ, be ye followers of me as I am of Christ, let this mind be in you which was also in Christ. Well what does that mean? We’re to be like Christ. What does it mean to be like Christ? Well for sure it means to be…what?…forgiving because that’s how we know Him as the one who forgave us all our sins.