John Chrysostom

"For though," saith he, "ye have ten thousand tutors in Christ, yet have ye not many fathers." He is not here setting forth his dignity, but the exceeding greatness of his love. Thus neither did he wound the other teachers: since he adds the clause, "in Christ:" but rather soothed them, designating not as parasites but as tutors those among them who were zealous and patient of labor: and also manifested his own anxious care of them. …

Homily on 1 Corinthians 13 ↗

Theophylact of Ohrid

Well then, you will say, do others not love you? They do, he says, but not as I do. For they are tutors, but I am a father. So with children, although there is one father, while there may be many tutors, yet the affection of all of them together toward the children is far less in comparison with the love of one alone, that is, the father: so it is likewise between us. Note, incidentally, that he added the words "in Christ" to the tutors; this was so as not to strike them down entirely. …

Commentary on 1 Corinthians ↗

Clement of Alexandria

A eunuch, then, does not mean a man who has been castrated, nor even an unmarried man, but a man who is unproductive of truth. Formerly he was "dry wood," but if he obeys the word and observes the sabbaths by abstaining from sins and keeps the commandments, he will be in higher honour that those who are educated in word alone and fail to do what is right. …

The Stromata Book 3 ↗

Thomas Aquinas

Secondly, he shows the correct way to admonish, saying: For though you have countless guides in Christ, you do not have many fathers. Here it should be noted that a father is one who begets, but a guide nurses and trains the child: "The law was our custodian until Christ came" (Gal 3:24). Therefore, the Apostle calls himself their father in Christ, because he was the first to preach the Gospel to them. Hence he assigns the reason for this when he continues: For I became your father in Christ Jesus through the gospel. …

Commentary on 1 Corinthians ↗