John Calvin Commentary Romans 15:8

"For I say that Christ hath been made a minister of the circumcision for the truth of God, that he might confirm the promises [given] unto the fathers," — Romans 15:8 (ASV)

Now I say, that Jesus Christ, etc. He now shows that Christ has embraced us all, so that he leaves no difference between the Jews and the Gentiles, except that in the first place he was promised to the Jewish nation and was, in a way, specially destined for them before he was revealed to the Gentiles. But he shows that concerning that which was the seed of all contentions, there was no difference between them; for he had gathered them both from a miserable dispersion and brought them, when gathered, into the Father’s kingdom, so that they might be one flock, in one sheepfold, under one shepherd. It is therefore right, he declares, that they should continue united together and not despise one another, for Christ despised neither of them.

He then speaks first of the Jews and says that Christ was sent to them to accomplish the truth of God by fulfilling the promises given to the Fathers. It was no common honor that Christ, the Lord of heaven and earth, put on flesh so that he might procure salvation for them. For the more he humbled himself for their sake, the greater was the honor he conferred on them.

But he evidently assumes this point as something unquestionable. It is all the more strange that there is such audacity in some fanatical minds that they do not hesitate to regard the promises of the Old Testament as temporal and to confine them to the present world.

And so that the Gentiles would not claim any excellency above the Jews, Paul expressly declares that the salvation Christ brought belonged by covenant to the Jews. For by his coming, he fulfilled what the Father had previously promised to Abraham, and thus he became the minister of that people. It therefore follows that the old covenant was in reality spiritual, though it was annexed to earthly types; for the fulfillment, of which Paul now speaks, must necessarily relate to eternal salvation.

Furthermore, to prevent anyone from quibbling and saying that such great salvation was promised to posterity when the covenant was entrusted to Abraham, he expressly declares that the promises were made to the Fathers. Therefore, either the benefits of Christ must be confined to temporal things, or the covenant made with Abraham must be extended beyond the things of this world.