The repeating theme of Paul's first missionary journey with Barnabas was: the gospel caused controversy (Acts 14:1-7).  But, although religious activists repudiated the teaching that Jesus is God's Messiah, many other Jews and Gentiles welcomed the message and were saved.  As the apostles reported back to the church in Antioch (in Syria), they spent time explaining how it pleased God to extend His grace to everybody who believes (Acts 14:27-28).

However, this news spread to the church in Jerusalem.  Some Jewish-background believers there still thought that only Jews could be saved, or that Gentiles could be saved if they were circumcised as Jews.  Despite the Jerusalem church previously dealing with this issue, when they agreed that Gentiles could be saved (Acts 11:1-18), some still believed that Paul and Barnabas were teaching error.  That is why they went to Antioch to persuade the church that all new believers had to become Jews.  They were sincere, but wrong: and the apostles refused to agree.  There was quite a debate.  Eventually it was clear that Paul and Barnabas, and other believers, should visit Jerusalem-based apostles (Peter, John and James the brother of Jesus), and ask them to say who was right (Acts 15:19).

As Paul and Barnabas travelled south through the Mediterranean coastlands and Samaria, they met with groups of new Christians.  They were greatly encouraged to hear that God wanted to include people from every racial group in His kingdom - because many Phoenicians and Samaritans did not have pure Jewish ancestry, they may have felt second class Christians.  Arriving in Jerusalem, most of the church was glad to see Paul and Barnabas.  The apostles and elders welcomed them as brothers and fellow-workers, and invited the missionaries to give a full account of their ministry.

It is still important to discern if teaching is true or false.  Failure to do so will reduce the gospel to powerless club-talk.  There is only one gospel which saves, and that is the gospel given by Jesus Christ to the apostles.  It is recorded faithfully in the book of Acts and in the apostolic letters.  Any other 'gospel' is either a subtraction from the real gospel or an addition: neither alternative has saving power (Galatians 1:6-9).  In the same way that Paul and Barnabas contended for the truth of the gospel, we should be very careful to do the same (Philippians 1:27-28).  A church which is not contending for the gospel is at risk of losing its privileged role as a light-bearer for Jesus (Revelation 2:5).  Believers can only have eternal confidence by staying firmly rooted in the apostolic gospel (Colossians 1:22-23).