In many of his letters, Paul emphasizes his apostleship. He was sent by Christ Jesus, the resurrected one. Time and again, he emphasizes his special calling. A different ministry was given to him than to the twelve.
Israel and the nations
For the twelve were sent to Israel (Matth. 10:5-6) and Jesus, during his stay here on earth, also (Matth. 15:24). Only when the Lord had risen did He call a 13th apostle from heaven: Paul. He received a different ministry than the twelve and was sent to the nations (Rom. 11:13). The gospel entrusted to Paul is therefore distinguished from that which was given to the twelve: the gospel of the uncircumcised as opposed to the gospel of the circumcised (Gal. 2:7).
my gospel
Whoever does not recognize this difference will get lost in the Bible and start mixing things up. Where God introduces differences, we should not unite them. Whoever reads the letters of Paul cannot escape the fact that he makes clear statements about this. He speaks of “my gospel” (Rom. 2:16, 2 Tim. 2:8), “our gospel” (2 Thess. 2:14), namely of Paul, Silvanus, and Timothy (:1), “the gospel that I preach among the nations” (Gal. 2:2), etc.
agreement
When he speaks in Galatians about the different ministries, Paul says that there was agreement between the twelve and himself regarding that diversity. Paul had a gospel for the nations; the twelve had a message for the Jewish people, circumcision.
Galatians 2
9 And when they acknowledged the grace that was given to me, James, Cephas, and John, who appear to be pillars, gave to me and Barnabas the right hand of fellowship: we, indeed, to the nations, and they to circumcision.