Whose minister was Paul not?
Paul was not a minister of Jerusalem, Judaism, or Peter and the eleven. He did not serve under their credentials or commendation. His ministry was challenged by Judaizers and others, but his proof was the converted pagans set on the rock Christ Jesus.
Les explains that Paul was constantly undermined by Judaizers from Israel, by the pagan world, and even by believing Jews from the element of the twelve in Jerusalem, who claimed he was an imposter and a false teacher because he lacked credentials. If he had letters of commendation from Peter, he would have had fewer problems, but he did not have that. All he had for proof of his ministry were the pagans who had been saved and set on the rock Christ Jesus. In 2 Corinthians, Paul says he will not blame the ministry but approves himself as a minister not of Jerusalem, not of Judaism, not of Peter and the eleven.