Albert Barnes Commentary Romans 11:13

"But I speak to you that are Gentiles. Inasmuch then as I am an apostle of Gentiles, I glorify my ministry;" — Romans 11:13 (ASV)

For I speak to you Gentiles. What I am saying concerning the Jews, I say regarding you who are Gentiles, to show you how you have been admitted to the privileges of the people of God; to stir your gratitude; and to warn you against abusing these mercies. As Paul also was appointed to preach to them, he had a right to speak to them with authority.

I am the apostle of the Gentiles. He was the apostle of the Gentiles not because other apostles did not preach to Gentiles (for they all did, except perhaps James), nor because Paul did not himself preach occasionally among the Jews; but because he was especially called to carry the gospel to the Gentiles and this was his original commission (Acts 9:15); because he was primarily employed in collecting and organizing churches in Gentile lands; and because the charge of the Gentile churches was especially entrusted to him, while that of the Jewish churches was especially entrusted to Peter. See Galatians 1:16; Ephesians 3:8; Galatians 2:7–8.

As Paul was especially appointed to this office, he claimed special authority to address those who were gathered into the Christian church from Gentile lands.

I magnify mine office. I honor (doxazw) my ministry; I esteem it of great importance; and by thus showing that the gospel is to be preached to the Gentiles, that the barrier between them and the Jews is to be broken down, and that the gospel may be preached to all people, I demonstrate that the office that proclaims this is one of significant honor. A minister may not magnify himself, but he may magnify his office. He may esteem himself as less than the least of all saints and unworthy to be called a servant of God (Ephesians 3:8), yet he may feel that he is an ambassador of Christ, entrusted with a message of salvation, entitled to the respect due to an ambassador, and to the honor that is appropriate for a messenger of God. To unite these two things constitutes the dignity of the Christian ministry.