“And above all these put on love, which binds everything together in perfect harmony. And let the peace of Christ rule in your hearts, to which indeed you were called in one body.” (Colossians 3:14-15a, ESV)
Paul offers words of wisdom to help believers grow into the image of Christ, to gain spiritual maturity. This does not involve learning spiritual secrets or following the law or adopting a severe lifestyle. The way we grow in Christ is by putting off our old way of living and thinking. When we became Christians we die to the old self and became new creatures in Christ. This death is symbolized by baptism which graphically proclaims that our entry into the kingdom of God only comes by death to self. This death must affect every aspect of our passions, lusts and selfish desires. This takes time and the disciplined work of the Holy Spirit to accomplish as He motivates us daily to set aside the old ways and put on the new.
And in this new life we are united to Christ and so to all other believers as well. Men and women, slave and free, black, white, yellow and brown we are all equal in Christ so we should treat everyone accordingly. We are to focus on being tender-hearted and kind toward all people. We are to forgive always even as we have been forgiven. We are never to seek our own agenda. This may disturb us because it will mean we will usually have to quietly accept abuse, scorn and reproach from our fellow human beings when we are really tempted to justify and defend ourselves to prove others wrong. The good Christian realizes however that his sense of worth and identity come from Christ not other men. We must always take care that what we say and do is tempered by love and humility.