John Chrysostom

"For though we walk in the flesh, we do not war according to the flesh." Here he goes on to alarm them also by the figure he uses, 'for,' says he, 'we are indeed encompassed with flesh; I own it, but we do not live by the flesh;' or rather, he said not even this, but for the present reserves it, for it belongs to the encomium on his life: but first discourseth of the Preaching, and shows that it is not of man, nor needeth aid from beneath. …

Homily 21 on 2 Corinthians ↗

Theophylact of Ohrid

That is, although we are clothed in flesh, we do not use carnal weapons. He reasons about preaching, showing that it is not a human affair and has no need of earthly help. And when he says "we wage war," he conveys this thought: we are waging war and have entered into battle.

Commentary on 2 Corinthians ↗

Clement of Alexandria

"I said, Ye are Gods; and all sons of the Highest." To whom speaks the Lord? To those who reject as far as possible all that is of man. And the apostle says, "For ye are not any longer in the flesh, but in the Spirit." And again he says, "Though in the flesh, we do not war after the flesh." "For flesh and blood cannot inherit the kingdom of God, neither doth corruption inherit incorruption." "Lo, ye shall die like men," the Spirit has said, confuting us.

The Stromata Book 2 ↗

Thomas Aquinas

But this reason is null and void; therefore, he destroys it, saying: For though we live in the world we are not carrying on a worldly war [according to the flesh]. As if to say: we cannot deny that we are in the flesh, because in Rom. (8:12) he says: "So then, brethren, we are debtors, not to the flesh, to live according to the flesh," but that we are ruled according to the flesh, by placing our end or our intention in carnal goods, this is false, because we are not carrying on a worldly war, i.e., we do not regulate our life, which …

Commentary on 2 Corinthians ↗