[Conservative til I die]

You are correct. But who was the founding apostle for the Gentile Church in the New Testament: Peter or Paul?

Neither, really. Paul founded many Churches (note the plural) and Peter said it would be wrong to exclude the Gentiles (see Cornelius the Centurion). However, Christ's message was for all, and even He laid the seeds for the Gentiles to be included when He healed the servant of the Roman Centurion because of the Centurion's faith in Him. Or when He prayed that all would be one (He did not qualify by saying "All Jews").

[Uncle Chip]

Read Galatians Chapter 2, Verses 7 thru 9: Paul says that from their council in Jerusalem [about 50 AD] forward he and Barnabas concentrated on the uncircumcision [Gentiles], while Peter [Cephas], James, and John [the 3 pillars of the Jewish Church] decided to concentrate on the circumcision [the Jews].

And by that time there were very few Jews left in Rome as Emperor Claudius [41-54AD] had commanded all Jews to depart from Rome as recorded in Acts 18:2. The Roman Church was Paul's ministry not Peter's. Paul was the authority for the Roman Church, not Peter.