Why were Paul and Barnabas brought up to Jerusalem?
Paul and Barnabas were brought to Jerusalem to settle the controversy with Peter and the eleven over Gentile salvation. Pharisees insisted Gentile believers had to be circumcised and keep the Law of Moses, while Paul taught salvation apart from Judaism, without circumcision or Law-keeping.
Les explains that this was the big controversy in Acts 15 between Peter and the eleven at Jerusalem and Paul, who had been dealing with Gentiles at Antioch. Paul told them the Gentiles were having salvation apart from Judaism, without circumcision and without being commanded to keep the Law. So Paul and Barnabas were brought all the way up to Jerusalem to try to settle the matter. Certain Pharisees who believed said it was needful to circumcise the Gentile believers and to keep the Law of Moses. Paul said no way, and there was a great confrontation and argument. Peter finally came to Paul's defense, remembering about fourteen years earlier at the house of Cornelius, where he had witnessed that God would save a Gentile without ascribing to Judaism, without repentance and water baptism.