Philippians is a positive letter of gratitude, but it also addresses a problem between coworkers.
Therefore, my brothers, whom I love and long for, my joy and crown, stand firm thus in the Lord, my beloved. I entreat Euodia and I entreat Syntyche to agree in the Lord. Yes, I ask you also, true companion, help these women, who have labored side by side with me in the gospel together with Clement and the rest of my fellow workers, whose names are in the book of life (Philippians 4:1-3).
Even the best Christians disagree, requiring extra work “to agree in the Lord.” It may take “help” from a trustworthy mediator. Sometimes, reconciliation is not immediate, as Paul himself knows. He and Barnabas have “a sharp disagreement” over taking Mark on their next missionary journey. Each defends an important principle. Paul sees Mark as unworthy since he deserted them previously (Acts 15:37-38 cf. Luke 9:62). Barnabas likely presses the principle of forgiveness (Luke 17:3-4). Neither backs down. So, “they separated from each other” (Acts 15:39). The situation is surely unpleasant for them and for the Antioch congregation, which seems to back Paul (Acts 15:40). This brief parting, however, does not affect their spiritual unity in Christ. The Lord uses their respective missions to double His outreach. All the resulting converts belong to one Lord, sharing one faith and one hope in one body. They certainly do not develop into separate movements, much less distinct denominations. Eventually, there is complete reconciliation as evidenced by Colossians 4:10 and 2 Timothy 4:11.
“They separated from each other.”