SOSTHENES (1 Corthians 1:1) was a common first-century name…
This name also appears in Acts 18:17. There Luke describes how someone with this name was beaten by a Jewish mob because he failed to make a case against Paul.
If the Sosthenes in Acts 18 is identical with the Sosthenes in 1 Corinthians 1:1, a remarkable conversion took place. Paul’s companion was the very man who had previously tried to prosecute him because of Christianity. If the two names refer to the same man, Sosthenes’ opposition to the gospel had been replaced by his active promotion of the gospel. The fact that only this man’s first name is mentioned indicates the Corinthians were very familiar with him. It is not too unrealistic to believe Luke and Paul described the same man. Brad Price, “First Corinthians,” p. 8.
“Then all the Greeks took Sosthenes, the ruler of the synagogue, and beat him before the judgment seat. But Gallio took no notice of these things” (Acts 18:17). “Paul, called to be an apostle of Jesus Christ through the will of God, and Sosthenes our brother” (1 Corinthians 1:1).