John Chrysostom

What does the "I know not" mean?-I am ignorant. And when could this ever happen? For nobody ever sinned in ignorance. Seest thou, that if we do not receive his words with the proper caution, and keep looking to the object of the Apostle, countless incongruities will follow? For if they sinned through ignorance, then they did not deserve to be punished. …

Homily on Romans 13 ↗

Theophylact of Ohrid

Here he speaks not of complete ignorance, for if they sinned in ignorance, then for what would they be punished? What then does he say? I remain in darkness, I am carried away, I do not know how sin carries me away. Therefore, when he says: "I do not understand," he indicates not ignorance of what ought to be done, but dangers, snares, seduction, enticement. All this he says about people who lived before the coming of Christ in the flesh, although he presented himself. …

Commentary on Romans ↗

Lucius Caecilius Firmianus Lactantius

Come, let us now consider whether a teacher sent from heaven can fail to be perfect. Let us suppose that some one were to be sent from heaven to instruct the life of men in the first principles of virtue, and to form them to righteousness. No one can doubt but that this teacher, who is sent from heaven, would be as perfect in the knowledge of all things as in virtue, lest there should be no difference between a heavenly and an earthly teacher. For in the case of a man his instruction can by no means be from within and of himself. …

The Divine Institutes Book 4, Chapter XXIV ↗

Thomas Aquinas

Then he clarifies what he had stated, when he says, for that which I work: first, that the law is spiritual; second, that man is carnal, sold under sin, now then it is no more. In regard to the first he does two things: first, he presents a proof; second, he draws the conclusion, at if then I do that which I will not. The proof is based on man's infirmity, which he first asserts; second, he gives the proof, at for the good which I will. …

Commentary on Romans ↗