But they have not all obeyed the Gospel - This seems to be the objection of a Jew; as if he had said: A Divine mission would be attended with success; whereas there are numbers who pay no attention to the glad tidings you preach. To this the apostle answers, that the Spirit of God, by Isaiah, Isaiah 53:1, foretold it would be so, even in the case of the Jews themselves, where he said, Lord, who hath believed our report? For although God brings the message of salvation to men, he does not oblige them to embrace it.

It is proposed to their understanding and conscience; but it does not become the means of salvation unless it be affectionately credited.

But they.

Romans 3:3 For what if some did not believe? shall their unbelief make the faith of God without effect?

Romans 11:17 And if some of the branches be broken off, and you, being a wild olive tree, were grafted in among them...

John 10:26 But you believe not, because you are not of my sheep, as I said to you.

Acts 28:24 And some believed the things which were spoken, and some believed not.

Hebrews 4:2 For to us was the gospel preached, as well as to them: but the word preached did not profit them...

1 Peter 2:8 And a stone of stumbling, and a rock of offense, even to them which stumble at the word, being disobedient...

obeyed.

Romans 1:5 By whom we have received grace and apostleship, for obedience to the faith among all nations, for his name:

Romans 2:8 But to them that are contentious, and do not obey the truth, but obey unrighteousness, indignation and wrath,

Romans 6:17 But God be thanked, that you were the servants of sin...

Romans 16:26 But now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting God...

Isaiah 50:10 Who is among you that fears the LORD, that obeys the voice of his servant, that walks in darkness, and has no light?...

Galatians 3:1 O foolish Galatians, who has bewitched you, that you should not obey the truth...

Galatians 5:7 You did run well; who did hinder you that you should not obey the truth?

2 Thessalonians 1:8 In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ:

Hebrews 5:9 And being made perfect, he became the author of eternal salvation to all them that obey him;

Hebrews 11:8 By faith Abraham, when he was called to go out into a place which he should after receive for an inheritance, obeyed; and he went out...

1 Peter 1:22 Seeing you have purified your souls in obeying the truth through the Spirit to unfeigned love of the brothers...

1 Peter 3:1 Likewise, you wives, be in subjection to your own husbands; that, if any obey not the word...

Lord.

Isaiah 53:1 Who has believed our report? and to whom is the arm of the LORD revealed?

John 12:38-40 That the saying of Esaias the prophet might be fulfilled, which he spoke, Lord, who has believed our report...

our report. Gr. the hearing of us, or, our preaching.

Christ the End of the Law
The reason why many do not come to Christ is not because they are not earnest, after a fashion, and thoughtful and desirous to be saved, but because they cannot brook God's way of salvation. "They have a zeal for God, but not according to knowledge," We do get them by our exhortation so far on the way that they become desirous to obtain eternal life, but "they have not submitted themselves to the righteousness of God." Mark, "submitted themselves," for it needs submission. Proud man wants to save …
Charles Haddon Spurgeon—Spurgeon's Sermons Volume 22: 1876

Which Sentence Dishonoreth the Holy Martyrs, Nay Rather Taketh Away Holy Martyrdoms Altogether. ...
3. Which sentence dishonoreth the holy Martyrs, nay rather taketh away holy martyrdoms altogether. For they would do more justly and wisely, according to these men, not to confess to their persecutors that they were Christians, and by confessing make them murderers: but rather by telling a lie, and denying what they were, should both themselves keep safe the convenience of the flesh and purpose of the heart, and not allow those to accomplish the wickedness which they had conceived in their mind. …
St. Augustine—Against Lying

Or Haply is it So, that He who Plots in this Way to Find...
13. Or haply is it so, that he who plots in this way to find out Priscillianists, denies not Christ, forasmuch as with his mouth he utters what with his heart he believes not? As if truly (which I also said a little above) when it was said, "With the heart man believeth unto righteousness," it was added to no purpose, "with the mouth confession is made unto salvation?" [2398] Is it not so that almost all who have denied Christ before the persecutors, held in their heart what they believed of Him? …
St. Augustine—Against Lying