Is the gospel Paul preached among the Gentiles the same gospel we must follow today?
Yes. Paul communicated the same gospel he preached among the Gentiles as the gospel we must adhere to today. It is called the gospel of grace, the gospel of God, and the gospel of Christ: that Christ died for our sins, was buried, and arose again from the dead the third day. There is no other gospel.
Les explains from Galatians 2 that Paul went up to Jerusalem by revelation and communicated to the Jewish believers there the gospel he preached among the Gentiles. That gospel was unique: Peter and the others had not preached Paul's gospel, and they had not preached it to Gentiles. Les notes that Peter had no ministry among Gentiles except Cornelius, which was a one-time thing. Paul makes it plain that the gospel he preached among the Gentiles is the gospel we must adhere to even today. Coming back to 1 Corinthians 15, Les says this gospel is called my gospel, the gospel of the grace of God, the gospel of God, the gospel of grace, and the gospel of Christ—titles for the three-pronged fact that Christ died for our sins, was buried, and arose again from the dead the third day. There is no other plan of salvation, no other gospel, and no other way.
And I went up by revelation, and communicated unto them that gospel which I preach among the Gentiles, but privately to them which were of reputation, lest by any means I should run, or had run, in vain.
More Questions
Was Paul's gospel the same one Peter and the other apostles preached?
The gospel Paul preached was unique: Peter and the other apostles had not preached Paul's gospel, and they certainly had not preached it to Gentiles.
Why did Paul specify that the gospel he communicated was the one he preached among the Gentiles?
The Holy Spirit inspired the stipulation about which gospel Paul preached because Paul's gospel to the Gentiles was totally different from what Peter and the eleven preached to the Jews.
Why does Paul's phrase 'that gospel which I preach among the Gentiles' show his gospel was different from Peter's?
The phrase 'that gospel, which I preach among the Gentiles' would be unnecessary wording if Paul had preached exactly the same gospel Peter did, so that wording itself signals a different gospel.