And not only now let us seem to believe and give heed, when we are admonished by the elders; but also when we take our departure home, let us remember the commandments of the Lord, and not be allured back by worldly lusts, but let us often and often draw near and try to make progress in the Lord's commands, that we all having the same mind may be gathered together for life.
The joy referred to here will come when the Corinthians mend their ways, after which it will be possible for them to mature in faith. But before that there will be consolation, enabling them to abandon the pleasure of the present in favor of hope for things to come. The peace of God is one thing, but the peace of the world is another. People in the world have peace, but it works to their damnation. The peace of Christ is free from sins, and therefore it is pleasing to God. A person who has peace will also have love, and the God of both will protect him forever.
What means, "for the rest, brethren, rejoice?" Thou hast pained, terrified, thrown them into an agony, made them to tremble and fear, and how biddest thou them rejoice? 'Why, for this very reason I bid them rejoice. For,' he says, 'if what is your part follow upon mine, there will be nothing to prevent that joy. For all my part has been done; I have suffered long, I have delayed, I have forborne to cut off, I have besought, I have advised, I have alarmed, I have threatened, so as by every means to gather you in unto the fruit of repentance. And now it behoveth that your part be done, and so your joy will be unfading.'
"Be comforted." For, since their trials were numerous, and their perils great, he says, '"be comforted," both by one another, and by us, and by your change unto the better. For if ye should have joy of conscience and become complete, nothing is wanting unto your cheerfulness and comfort. For nothing doth so produce comfort as a pure conscience, yea, though innumerable trials surround.'
"Be of the same mind, live in peace." The request he made in the former Epistle also, at the opening. For it is possible to be of one mind, and yet not to live in peace, [for instance], when people agree in doctrine, but in their dealings with each other are at variance. But Paul requires both.
"And the God of love and peace shall be with you." For truly he not only recommends and advises, but also prays. For either he prays for this, or else foretells what shall happen; or rather, both. 'For if ye do these things,' he says, 'for instance, if ye be "of one mind" and "live in peace," God also will be with you, for He is "the God of love and of peace," and in these things He delighteth, He rejoiceth. Hence shall peace also be yours from His love; hence shall every evil be removed. This saved the world, this ended the long war, this blended together heaven and earth, this made men angels. This then let us also imitate, for love is the mother of countless good things. By this we were saved, by this all those unspeakable good things [come] to us.'
[AD 140] Pseudo-Clement on 2 Corinthians 13:11