Rom 10:20

“"But Esaias is very bold, and saith." Now what he means is something of this kind. He put a violence on himself, and was ambitious to speak, not something veiled over, but to set things even naked before your eyes, and choosing rather to run into dangers from being plain spoken, than by looking to his own safety, to leave you any shelter for your impenetrableness; although it was not the manner of prophecy to say this so clearly; but still to stop your mouths most completely, he tells the whole beforehand clearly and distinctly. The whole! what whole? Why your being cast out, and also their being brought in; speaking as follows, "I was found of them that sought Me not, I was made manifest of them that asked not after Me." Who then are they that sought not? who they that asked not after Him? Clearly not the Jews, but they of the Gentiles, who hitherto had not known Him. As then Moses gave their characteristic mark in the words, "no people" and "a foolish nation," so here also he takes the same ground to point them out from, viz. their extreme ignorance. And this was a very great blame to attach to the Jews, that they who sought Him not found Him, and they who sought Him lost Him.”

“Having said that Moses speaks first, he mentions also another prophet, who says the same thing more clearly and openly. Isaiah, he says, "is very bold," that is, he strove to express the truth in all its nakedness and preferred to expose himself to danger rather than remain silent. "I was found," it says in him, "by those who did not seek Me" and who did not ask for Me (Isa. 65:1). Those whom Moses called a foolish nation, Isaiah named as those who neither sought nor asked, that is, ignorant people and enemies of knowledge. So from all this the Jews should have understood that some were rejected and others were accepted.”

“Second, he shows that they knew through the teaching of the prophets, and first he quotes Isaiah as foretelling the conversion of the gentiles, saying, but Isaiah is bold and says, i.e., Isaiah boldly declares the truth, although this would put him in danger of death: he goes forth boldly to meet armed men (Job 39:21). And says: I was found by those who did not seek me; I appeared openly to those who did not ask for me; here our text has: they have sought me who before asked not for me, they have found me who sought me not (Isa 65:1). He mentions first the conversion of the gentiles, saying, I was found by those who did not seek me. This shows that the conversion of the gentiles was beyond their merits and intention: Christ became a servant in order that the gentiles might glorify God for his mercy (Rom 15:9). About this finding Matthew says: the kingdom of heaven is like a treasure in a field, which a man found (Matt 13:44). Second, he shows the cause and manner of their conversion. The cause, indeed, because it was not by chance that they found what they were not seeking but by the grace of him who willed to appear to them. This is indicated, when he says: I appeared; the grace of God has appeared for the salvation of all men (Titus 2:11). The manner was that Christ did not appear to the gentiles in the enigmas and figures of the law but in plain truth; hence he says: I appeared openly. Behold, now you speak plainly and do not speak a proverb (John 16:29). I appeared openly to those, i.e., the gentiles, who did not ask after me, i.e., who did not ask for my doctrine: they keep on praying to a god that cannot save (Isa 45:20).”