Luke may have intended this group of "about12" to remind the reader of another core group, the12apostles, though these were not on the same level of authority. The Ephesian church became the center of Christian witness in western Asia Minor and the Aegean region as Antioch and Jerusalem had become earlier. [source][source][source]
Context Summary
Acts 19:1-12 - The Holy Spirit Working In Ephesus
Paul had planted good seed at Corinth, and Apollos, in turn, had watered it, 1 Corinthians 3:6. Large numbers became his devoted followers. This, however, excited no jealousy in Paul. Apollos and he were only instruments through whom God was pleased to work.
Meanwhile Paul had a ministry to fulfill in Ephesus. The twelve men mentioned had known only so much of the truth as had been revealed to the Baptist. They had felt the need of repentance and had heard of Christ as the Lamb of God; but of His resurrection and ascension and the gift of the Holy Spirit they were ignorant. Paul at once fixed on this lack as the source of their impotence. He seemed to say, "If you men had received the baptism of the Spirit, you would move this city."
It was wise on Paul's part to remove the disciples and his work to their own premises, which soon became famous throughout the city and indeed throughout the adjacent country. People who had come in to worship at the shrine of Diana gave themselves to Christ, and the Christian faith became disseminated through the province, Ephesus itself being mightily moved. [source]
Chapter Summary: Acts 19
1The Holy Spirit is given by Paul's hands 8The Jews blaspheme his doctrine, which is confirmed by miracles 13The Jewish exorcists, 16are beaten by a man who had an evil spirit 19Conjuring books are burnt 21Demetrius, for love of gain, raises an uproar against Paul; 35which is appeased by the town clerk