The apostle Paul had a major toe-to-toe with Peter in Antioch, a city north of the Land of Israel. Here is the passage and it reveals Paul’s gospel:

11 When Peter came to Antioch, I opposed him to his face, because he was clearly in the wrong. 12 Before
certain men came from James, he used to eat with the Gentiles. But when
they arrived, he began to draw back and separate himself from the
Gentiles because he was afraid of those who belonged to the
circumcision group. 13 The other Jews joined him in his hypocrisy, so that by their hypocrisy even Barnabas was led astray. 14 When
I saw that they were not acting in line with the truth of the gospel, I
said to Peter in front of them all, “You are a Jew, yet you live like a
Gentile and not like a Jew. How is it, then, that you force Gentiles to
follow Jewish customs?

15 “We who are Jews by birth and not ‘Gentile sinners’ 16 know
that a man is not justified by observing the law, but by faith in Jesus
Christ. So we, too, have put our faith in Christ Jesus that we may be
justified by faith in Christ and not by observing the law, because by
observing the law no one will be justified.

The situation and the details cannot be examined in this context: Paul and Barnabas had evangelized Antioch; a church had formed; the church was a fellowship of Jewish believers and Gentile believers; they ate with one another; Peter ate with them when he was there. Then the “men from James” [brother of Jesus, leader of the church of Jerusalem] arrived in Antioch and Peter slipped into another space so as to avoid the appearance of confusing the men from James by his behavior. The men from James were Torah observant and must have understood Peter’s behavior as non-observant behaviors.

Paul tells us that Peter’s behavior was eating with Gentiles.
Paul also tells us that Peter’s separation led to others doing the same thing.
And Paul tells us that this behavior of separating from Gentile believers was hypocrisy and…

Our gospel text today is Gal 2:14 where Paul says that Peter’s behaviors were contrary to the gospel.