Expositor's Bible Commentary Commentary Acts 18:27

"And when he was minded to pass over into Achaia, the brethren encouraged him, and wrote to the disciples to receive him: and when he was come, he helped them much that had believed through grace;" — Acts 18:27 (ASV)

A number of people who identified themselves in some way with the Gospel were at Ephesus before Paul began to minister there—people like Priscilla and Aquila who understood clearly, like Apollos whose understanding was growing, or like those mentioned in 19:1–7, 13–16, whose faith was to some extent deviant. When Apollos desired to visit Achaia, apparently on behalf of the Gospel, the Christians of Ephesus encouraged him and sent along a letter of commendation, probably written by Priscilla and Aquila, to the believers at Corinth. There he vigorously debated with the Jews and showed from the OT that Jesus was the Messiah. People in the Corinthian church obviously thought highly of him, as Paul also did later (see 1Colossians 1–4).