John Chrysostom

"Now concerning things sacrificed to idols, we know that we all have knowledge." Leaving alone the weak, which he always doth, he discourses with the strong first. And this is what he did also in the Epistle to the Romans, saying, "But thou, why dost thou judge thy brother?" for this is the sort of person that is able to receive rebuke also with readiness. Exactly the same then he doth here also. …

Homily on 1 Corinthians 20 ↗

Theophylact of Ohrid

Some of the Corinthians were perfect, and knowing that what enters the mouth does not defile a person (Matt. 15:11) and that idols are wood and stone and cannot cause harm, they indiscriminately entered idol-temples and ate food sacrificed to idols. Others, less perfect, seeing such people, themselves also entered idol-temples and offered sacrifices to idols, but not with the same thought as the first group, but thinking that the idols were worthy of honor and capable of receiving sacrifices. …

Commentary on 1 Corinthians ↗

Irenaeus

It is therefore better and more profitable to belong to the simple and unlettered class, and by means of love to attain to nearness to God, than, by imagining ourselves learned and skilful, to be found [among those who are] blasphemous against their own God, inasmuch as they conjure up another God as the Father. …

Against Heresies Book II ↗

Augustine of Hippo

Paul means that knowledge only does good in company with love. Otherwise it merely puffs a man into pride.

City of God 9.20 ↗

Bonaventure

"Knowledge puffs up, but charity edifies"; therefore it is necessary to join charity with knowledge, so that a man may have knowledge and charity together, so that what the Apostle says may be fulfilled: "Rooted and founded in charity, that you may be able to comprehend with all the Saints what is the length, and breadth, and height, and depth, and to know also the charity of Christ which surpasseth knowledge." This is the knowledge which is a gift of the Holy Spirit.

Collationes de Septem Donis, Collation 4 ↗