1-2 examples does not make a general rule throughout throughout the entire Mediterranean area. Paul was a Jew and he was persecuted throughout his ministry. Former pagan gentiles would not have been welcomed in the synagogues. Jesus said His followers would be thrown out of the synagogues and killed, not welcomed. Paul got in Peter's face because he would not fellowship with gentiles when Jews from Jerusalem came around.
John 16:2 They shall put you out of the synagogues: yea, the time cometh, that whosoever killeth you will think that he doeth God service
Galatians 2:11-14
(11) But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed.
(12) For before that certain came from James, he did eat with the Gentiles: but when they were come, he withdrew and separated himself, fearing them which were of the circumcision.
(13) And the other Jews dissembled likewise with him; insomuch that Barnabas also was carried away with their dissimulation.
(14) But when I saw that they walked not uprightly according to the truth of the gospel, I said unto Peter before them all, If thou, being a Jew, livest after the manner of Gentiles, and not as do the Jews, why compellest thou the Gentiles to live as do the Jews?