New Defender's Study Bible Notes
1:1 Sosthenes. “Sosthenes,” until just a short time before, had been ruler of the Jewish synagogue at Corinth (Acts 18:17), even suffering a beating by the Corinthian Greeks because of his involvement with the Jewish insurrection against Paul (Acts 18:12). Somehow the Lord had used these experiences to bring Sosthenes to believe Paul and accept Christ. He had even gone to Ephesus with Paul, and now was joining Paul in his letter back to his Christian friends in Corinth (I Corinthians 16:5-8; Acts 20:31.