Why were Paul and Barnabas sent to Jerusalem?
Paul and Barnabas were sent to Jerusalem by the Lord's direction after many years of conflict came to a head. They went to confront Peter and the hierarchy in Jerusalem regarding the Judaizers who insisted Gentile converts must keep the Law of Moses and practice circumcision.
Les explains that the church in Antioch, up in Syria, had become predominantly Gentile, where Paul and Barnabas labored and moved out into the Gentile world of Asia Minor and Greece. Everywhere they went, their little congregations were constantly subjected to Judaizers trying to bring them back under the Law, claiming Paul's converts could not be saved unless they kept the Law of Moses, practiced circumcision, and so forth. After many years this came to a head, and Paul and Barnabas by the Lord's direction were sent up to Jerusalem to confront Peter and the hierarchy there. Paul rehearses this in Galatians chapter 2, and Luke's account of the same meeting is in Acts chapter 15.