John Chrysostom

Yet even this is no disparaging of the flesh. For so long as it keeps its own place, nothing amiss cometh to pass. But when we let it have its own will in everything, and it passes over its proper bounds, and rises up against the soul, then it destroys and corrupts everything, yet not owing to its own nature, but to its being out of proportion, and the disorder thereupon ensuing. "But they that are after the Spirit do mind the things of the Spirit."

Homily on Romans 13 ↗

Theophylact of Ohrid

Those who have given themselves over, he says, to the immoderate slavery of the flesh always think about fleshly things and never contemplate the divine, but those who have wholly submitted themselves to the Spirit both think and do everything spiritual.

Commentary on Romans ↗

Clement of Alexandria

It is possible to think of those who have just recently been instructed in the faith and who are still little ones in Christ as carnal, for he calls those who have already believed by the Holy Spirit "spiritual" and those newly taught and not yet purified "carnal." He speaks of these latter as carnal with good reason, for like the pagans they still mind the things of the flesh.

The Instructor Book 1 ↗

Thomas Aquinas

Then when he says "for they who are according to the flesh," he proves what he had said. And he brings in two syllogisms. One is on the side of the flesh, and runs like this: All who follow the prudence of the flesh are brought to death; but those who walk according to the flesh follow the prudence of the flesh. Therefore, all who walk according to the flesh are brought to death. …

Commentary on Romans ↗