15 And let the peace of God rule in your hearts, to the which also ye are called in one body; and be ye thankful.
[AD 407] John Chrysostom on Colossians 3:15
"And let the peace of God rule in your hearts, to the which also ye were called in one body; and be ye thankful."

"The peace of God." This is that which is fixed and steadfast. If on man's account indeed thou hast peace, it quickly comes to dissolution, but if on God's account, never. Although he had spoken of love universally, yet again he comes to the particular. For there is a love too which is immoderate; for instance, when out of much love one makes accusations without reason, and is engaged in contentions, and contracts aversions. Not this, saith he, not this do I desire; not overdoing things, but as God made peace with you, so do ye also make it. How made He peace? Of His own will, not having received anything of you. What is this? "Let the peace of God rule in your hearts." If two thoughts are fighting together, set not anger, set not spitefulness to hold the prize, but peace; for instance, suppose one to have been insulted unjustly; of the insult are born two thoughts, the one bidding him to revenge, the other to endure; and these wrestle with one another: if the Peace of God stand forward as umpire, it bestows the prize on that which bids endure, and puts the other to shame. How? by persuading him that God is Peace, that He hath made peace with us. Not without reason he shows the great struggle there is in the matter. Let not anger, he saith, act as umpire, let not contentiousness, let not human peace, for human peace cometh of avenging, of suffering no dreadful ill. But not this do I intend, he saith, but that which He Himself left.

He hath represented an arena within, in the thoughts, and a contest, and a wrestling, and an umpire. Then again, exhortation, "to the which ye were called," he saith, that is, for the which ye were called. He has reminded them of how many good things peace is the cause; on account of this He called thee, for this He called thee, so as to receive a worthy prize. For wherefore made He us "one body"? Was it not that she might rule? Was it not that we might have occasion of being at peace? Wherefore are we all one body? and now are we one body? Because of peace we are one body, and because we are one body, we are at peace.

[AD 407] John Chrysostom on Colossians 3:15
"And be ye thankful." For this is to be thankful, and very effectively, to deal with his fellow-servants as God doth with himself, to submit himself to the Master, to obey; to express his gratitude for all things, even though one insult him, or beat him.

For in truth he that confesses thanks due to God for what he suffers, will not revenge himself on him that has done him wrong, since he at least that takes revenge, acknowledges no gratitude. But let not us follow him (that exacted) the hundred pence, lest we hear, "Thou wicked servant," for nothing is worse than this ingratitude. So that they who revenge are ungrateful.

[AD 1107] Theophylact of Ohrid on Colossians 3:15
Often we are offended by someone, and then two thoughts struggle within us, one of which urges revenge, while the other urges long-suffering. If the peace of God stands within you as the distributor of rewards, that is, as judge and recompenser, then it gives the reward to the thought which commands endurance, and silences the other. Therefore, let the peace of God be the distributor of rewards in you, and not anger, nor contentiousness, nor human peace: for human peace comes from vengeance and retaliation. But the peace of God, constant and inviolable, is not concluded for the sake of any worldly good, just as in relation to us the peace of God was not concluded for the sake of any merits, but simply out of mercy and love He destroyed the enmity that existed against us. Why then, having reminded us of love, does he again begin to speak about peace? It would seem to be a superfluous exhortation, since peace is already contained in love. Perhaps this is said because often even a friend accuses his friend, and from excessive love disputes, offenses, and clashes frequently arise. This is not what I want, he says, but with love have the peace of God, which orders all things and resolves all things.

That is, Christ, calling us to peace, made us one body, Himself becoming the Head. For what other reason are we one body, if not so that, being members of one body to each other, we would keep peace among ourselves and not be divided? Or because you are called to peace, that is, deemed worthy through peace of countless blessings. For if we had not been reconciled with God, we would not have been called to be His servants and partakers of His blessings.

A person is friendly who acts in the same way toward his fellow servants as God acts toward him. One who confesses the grace of God and thanks God for the forgiveness of his sins will not take revenge on the one who did not justify him; and conversely, the one who takes revenge clearly does not remember what a great benefaction he himself received in the forgiveness of sins, like the one who received the remission of ten thousand talents and was unwilling to forgive a hundred denarii (Matt. 18:24). Therefore, let us be grateful for everything, whatever we may suffer and from whomever we may suffer it, and we shall receive the crown of martyrdom.