The successful alliance of Paul and Barnabas broke up unexpectedly over a disagreement regarding John Mark rejoining the alliance. Paul held on to a position that John Mark could not be relied upon as a team member because he deserted the team in an earlier mission. In contrast, Barnabas was adamant on giving John Mark a second chance. They broke up over the “sharp disagreement” and continued with their mission as two separate teams [Acts 15:39–41].
However, their ministry (then two separate ministries) was not diminished: Paul teamed with Silas, Timothy, and others to spread the gospel through Macedonia and Greece. Barnabas successfully mentored Mark, who went on to write the second gospel. Later events showed they remained in good terms and showed interest in each other’s ministry as evidenced by Paul inviting Mark later to join his ministry. Also, Paul’s later interactions with Oneismus and Philemon indicate increased willingness to grant a “second chance” as he judged appropriate. Over all, we learn from Paul-Barnabas breakup that an alliance for the gospel or other human endeavor could experience problems including breakup but such problems need not result in diminished focus on the bigger picture.