“Paul, called to be an apostle of Jesus Christ through the will of God, and Sosthenes our brother,”
King James Version (KJV)
1:1 Paul, called to be an apostle - There is great propriety in every clause of the salutation, particularly in this, as there were some in the church of Corinth who called the authority of his mission in question. Through the will of God - Called the commandment of God, #1Tim 1:1 This was to| the churches the ground of his authority; to Paul himself, of an humble and ready mind. By the mention of God, the authority of man is excluded, #Gal 1:1|; by the mention of the will of God, the merit of Paul, #1Cor 15:8|, &c. And Sosthenes - A Corinthian, St. Paul's companion in travel. It was both humility and prudence in the apostle, thus to join his name with his own, in an epistle wherein he was to reprove so many irregularities. Sosthenes the brother - Probably this word is emphatical; as if he had said, Who, from a Jewish opposer of the gospel, became a faithful brother.
1Co 1:1 The Divisions in the Church Brought to Light SUMMARY OF I CORINTHIANS 1: Greetings to the Church. Thanksgiving for the Grace of God. An Exhortation to Unity. Schisms Rebuked. The Sin of Honoring Human Leaders Instead of Christ. The Preaching of the Cross the Power of God to Salvation. Not the Worldly Wise and Proud, but the Humble and Lowly. Converted. Paul, called [to be] an apostle of Jesus Christ. Some of the Judaizing teachers, who had visited the church at Corinth after the departure of Paul, in order to lessen his authority, had asserted that he was not an apostle, divinely called like the Twelve. Hence, at the beginning, he asserts his apostleship, and refers to his divine call. See 1Co 9:1 2Co 12:12. Sosthenes, [our] brother. A Sosthenes, who was then the chief ruler of the synagogue at Corinth, is named in Ac 18:17. The Sosthenes whom Paul associated with himself in the letter must have been well known to, and influential among, the Corinthians, and was probably the former chief ruler, who had been converted. Apollos, Priscilla and Aquila, all well known to the church, were at Ephesus with Paul (1Co 16:12,19), but Sosthenes is chosen to appear with him in the salutation.