Cyril of Alexandria

The unbelieving Jews were clearly sick with bitter and unholy conceptions of our Savior Christ. They thought that the Holy Virgin had been corrupted—I mean the Lord's mother—and that she gave birth to a child conceived not of the Holy Spirit or of operation from above but rather conceived by one of those on the earth. …

Commentary on the Gospel of John, Book 5 ↗

Theophylact of Ohrid

And they again say: "We were not born of fornication; we have one Father, God." See what arrogance! The Lord denies their kinship even with Abraham, yet they are so vainglorious that in their madness they call themselves children of God Himself. They boast of divine sonship, probably because they had heard the words "Israel is My firstborn son" (Ex. 4:22). But they should have known that God also said in another place: "I have nourished and brought up children, and they have rebelled against Me" (Is. 1:2). …

Commentary on John ↗

Augustine of Hippo

"Then said they to Him, We be not born of fornication; we have one Father, even God." Abraham has now lost his importance. For they were repulsed as they ought to have been by the truth-speaking mouth; because such was Abraham, whose deeds they failed to imitate, and yet gloried in his lineage. And they altered their reply, saying, I believe, with themselves, As often as we name Abraham, he goes on to say to us, Why do ye not imitate him in whose lineage ye glory? Such a man, so holy, just, and guileless, we cannot imitate. …

Tractates on John 42 ↗

Thomas Aquinas

Then when he says, you do what your father did, he draws his conclusion. It was like saying: from the fact that you do not do the works of Abraham, it follows that you have some other father whose works you are doing. A similar statement is made in Matthew (23:32): "Fill up, then, the measure of your fathers." Then when he says, they said to him, we were not born of fornication, he shows that they do not take their origin from God, for since they knew from our Lord's words that he was not speaking of carnal descent, they turn to …

Commentary on John ↗

Bonaventure

"But you do the works of your father." Chrysostom: "The works of Abraham were faith, obedience, meekness: yours, unfaithfulness, impiety, and cruelty." "They therefore said to him." Here it is shown that they are not children of God. For since they had already understood that he was speaking of a spiritual father, therefore they commend themselves as being children of God, as worshipers of him, not given over to idolatry, which is called fornication in Scripture; whence he says: "They therefore said to him: We are not born of …

Commentary on John, Chapter 8 ↗