These instructions close the epistle. From chapter 15:8, it is the exordium, the personal circumstances of the apostle, and salutations.
In verses 8 to 12, he sums up his thoughts respecting God's dealings with the Jew and the Gentile in the advent of Jesus. He was a minister of the circumcision for the truth of God, to accomplish the promises made to the fathers. For to the Jews God had made promises; but none to the Gentiles. To the latter it was not truth that was in question: but by grace they might through Jesus glorify God for His mercy. For them the apostle quotes passages from Deuteronomy (that is to say, from the Law), from the Psalms, and from the Prophets.
In verse 13, he turns affectionately to the Romans to express his desires for them, and his confidence in the blessing they had received from God, which enabled them mutually to exhort one another, while expressing at the same time his boldness in some sort, because of the grace God had given him, to be the minister of Jesus Christ to the Gentiles by fulfilling a public function with regard to them; being, as it were, a priest to offer up the Gentiles as an offering acceptable to God, because sanctified by the Holy Ghost (see Num. 8:11). This was his glory before God. This sanctification by the Holy Ghost was that which took the place of sanctification by birth, and it was well worth it.
Moreover he had accomplished his task from Jerusalem round about to Illyricum; notwhere Christ had been preached before, but where they had not yet heard of Him. This had prevented his coming to Rome. But now that there was no more place for him, according to the Holy Ghost-nothing more in those parts for him to do, and having long desired to see them, he thought to visit them on his way to Spain. For the moment he was going to Jerusalem with the collection made in Macedonia and Achaia for the saints.
We see that his heart turns to the Jews; they occupied his thoughts; and while desiring to put the seal of performance on the grace which this collection betokened, he was pre-occupied with them as Jews, as those who had a claim: a mingled feeling perhaps of one who was anxious to shew that he did not forget them; for, in fact, he loved his nation. We have to learn whether, in executing this service (properly that of a deacon), pleasing as it might be, he was at the height of his mission as apostle. However that might be, the hand of God was in it to make all things work for the good of His beloved servant and child, as well as for His own glory. Paul had a presentiment that it would not perhaps turn out well, and he asks the prayers of the saints at Rome, that he might be delivered from the hands of the wicked, and see their face with joy. We know how it ended: the subject was spoken of when we were considering the Acts. He saw them indeed at Rome; he was delivered, but as a prisoner; and we do not know if he ever went to Spain The ways of God are according to His eternal counsels, and according to His grace, and according to His perfect wisdom.