John Chrysostom

"That whilst we are at home in the body, we are absent from the Lord (for we walk by faith, not by sight); we are of good courage, I say, and are willing to be absent from the body, and to be at home with the Lord." That which is greater than all he has put last, for to be with Christ is better, than receiving an incorruptible [body.] But what he means is this: 'He quencheth not our life that warreth against and killeth us; be not afraid; be of good courage even when hewn in pieces. …

Homily 10 on 2 Corinthians ↗

Theophylact of Ohrid

Then, lest someone say: so then what? does the body alienate us from God? — he deflected this objection by saying: "for we walk by faith, not by sight," that is, although even here we know Him, yet only in part, for this is what "by faith" means, and not face to face, which is what "by sight" means.

Commentary on 2 Corinthians ↗

Clement of Alexandria

And he anointed not him that was comely in person, but him that was comely in soul. If, then, the Lord counts the natural beauty of the body inferior to that of the soul, what thinks He of spurious beauty, rejecting utterly as He does all falsehood? "For we walk by faith, not by sight." Very clearly the Lord accordingly teaches by Abraham, that he who follows God must despise country, and relations, and possessions, and all wealth, by making him a stranger. …

The Instructor Book 3 ↗

Thomas Aquinas

That we are absent from the Lord is proved, when he says, for we walk by faith, i.e., we pass through this life in faith, and not by sight: because faith deals with things not seen. For the word of faith is as a lamp with which the road is lit in this life: "Your word is a lamp to my feet, and a light for my steps" (Ps. 119:105). But in heaven there will be no such lamp, because the radiance of God, i.e., God himself, has enlightened it (Rev. 21:23). Therefore, we shall then see him by sight, i.e., in his essence. …

Commentary on 2 Corinthians ↗