John Chrysostom

"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. …

Homily 30 on 2 Corinthians ↗

Theophylact of Ohrid

I, he says, have done my part; it remains for you to act in accordance with me. For if you correct your life, you will gain unfading joy in your conscience, even though I grieved you with my words. That is, be perfect both in teaching and in life, and supply that which is lacking in you. Since there were many temptations and dangers, he says to them: seek consolation in yourselves, in one another, and in your own change for the better; for a good conscience is a great consolation. …

Commentary on 2 Corinthians ↗

Thomas Aquinas

Having rebuked those deceived by false apostles, the Apostle now comforts those who have persisted in his faith and doctrine. First, he gives an admonition; secondly, he adds a greeting (v. 12). In regard to the first he does two things. First, he gives the salutation; secondly, the reward of a fulfilled admonition (v. 11d). But he admonishes them on three points: first, what they should have been in themselves; secondly, in regard to their neighbor (v. 11b); thirdly, how all should act towards one another (v. 11c). …

Commentary on 2 Corinthians ↗