John Chrysostom

Here he seems to me to be giving a gentle warning to the more advanced on the score of vanity. And what he says is this, Dost thou wish to show me that thou art perfect, and fully furnished? Do not show it to me, but let thy conscience suffice. And by faith, he here means that concerned not with doctrines, but with the subject in hand. For of the former it says, "With the mouth confession is made unto salvation" (Rom. x. 10); and, "Whosoever shall deny Me before men, him will I also deny." (Luke ix. …

Homily on Romans 26 ↗

Theophylact of Ohrid

Here he secretly hints that the mature one was displaying his maturity out of vainglory. He says: you want to show me that you are mature in faith regarding food, believing that everything is good and clean? Do not show me, but be content with the testimony of conscience before God, to Whom you show this. Even if no one else sees your blessedness, be content with yourself, if you yourself do not condemn yourself and your conscience does not condemn you in a matter that you have approved or chosen. …

Commentary on Romans ↗

Thomas Aquinas

Third, he rejects an excuse. For someone might say: although my neighbor may be scandalized at my eating all foods indiscriminately, yet to profess my faith, which tells me that it is lawful, I will use food indiscriminately. But the Apostle rejects this reasoning, saying: do you, who would use all foods indiscriminately, have faith, through which it is clear that it is lawful to use these foods. …

Commentary on Romans ↗