What does 1 Corinthians 11:19 mean?
Reports have come to Paul that the church in Corinth is even divided in their practice of the Lord's Supper. He now says this is believable. Part of that is because the believers in Corinth were separating into cliques based on loyalty to certain teachers (1 Corinthians 1:11–12).Paul also says he can believe this because factions reveal who is genuine in the practice of their faith in Christ. Put another way, divisions over issues such as these clarify which of them has God's approval for their faithfulness in doing what is right. If misunderstood, this statement would seem contradictory. Paul has spent much of the letter telling believers to avoid divisions (1 Corinthians 1:10) and to set aside their own "rights" for the good of others (1 Corinthians 8:12–13). To call factions desirable would turn those prior statements upside down.
However, that is neither what Paul has said, nor what he means. He has referred to this type of division as something expected, not something appreciated. Why are factions or divisions necessary to reveal who is approved of by God? Wouldn't unity among all the people show that all were being genuine in their faith? In practical terms, division, though never desirable, sometimes serves the purpose of showing who has the conviction to stand for what is right even when others are not doing so.