Before moving on, I wish to say something more about the disciples whom Paul met at Ephesus, when he returned to the province of Asia through the interior regions, after strengthening the Galatian churches he raised up earlier (Acts 18:21-23). When we begin reading Acts 19 we are struck with something new. Luke has Paul meeting with certain disciples before going into the synagogue to preach to the Jews. The oddity is so different from what Paul usually does that it has been suggested that the reading of the occurrence is too difficult, and “If there were any authority in manuscript or ancient versions to omit the episode, one would be inclined to take that course.”
Luke says nothing of these disciples, or why they had escaped the attention of Aquila and Priscilla. Who were they? Were they Jewish residents of Ephesus who had made a pilgrimage to Jerusalem during John’s ministry? Pilgrims who visited Jerusalem from other parts of the Empire, as a matter of course, did so only once or twice in a lifetime. Were they traveling disciples of John like Apollos, preaching John’s baptism? There is evidence of John’s ministry extending well into the fourth century AD, so there is little doubt that it was a strong movement even in Paul’s day. Were they Jews who were converted to John’s theology by traveling disciples of John, like Apollos (Acts 18:24-26)? Personally, I believe this last option, but it must be underscored that Luke simply doesn’t tell us. Nevertheless, he begins Paul’s ministry in the province of Asia with these men.
It has been said that these men must have known about Jesus and were, in fact, his disciples, simply because Luke uses disciples in Acts only to refer to followers of Jesus, but this is not what the text says. While they indeed may have known about Jesus (for John pointed to Jesus), and may even have had an eschatological doctrine concerning his return, the text says they knew only of John’s baptism. They were John’s disciples, not Jesus’ disciples. Furthermore, Luke says in Acts 19:5 that these men were baptized in the name of Jesus after Paul explained the difference between John and Jesus. This is the only mention of an occurrence of a re-baptism in the NT, so why would it be out of the question for these men to be John’s disciples? The argument against this obvious meaning is not strong enough, and leads to other questions, like why would they need another baptism, if they were Jesus’ disciples already? We need to simply let the Scripture tell us what it means, rather than doubting and trying to prove our doubts.
When people were baptized, they were baptized into the name of the one they followed, hence their being his disciples; they learned and followed their master’s or teacher’s doctrine. Luke is not trying to draw a line between water baptism and baptism of the Spirit, as some believe. Paul asked these men: “Into what where you baptized?” and their reply clearly indicated they were not Messianic or Christian. The washing of water in the name of Jesus and receiving the Holy Spirit belong indissolubly together. We cannot separate the two as Acts 8:14-17 clearly shows us. There was a reason for the delay in Acts 8. There existed centuries of religious competition between the Jews and the Samaritans concerning whose faith was authentic. The Samaritans needed to be pointed toward Jerusalem, lest error immediately set in and a split occur. So, too, there was a competition in the minds of John’s disciples and Jesus’ ministry (John 3:26), and we need to keep in mind that even John didn’t understand the things Jesus said (Luke 7:19-20).
John’s baptism was one of repentance that pointed his disciples to the coming of the One who would judge all. John’s work was that of a servant that prepared others for Jesus, whom he confessed was mightier than he. When folks were baptized in the name of Jesus, they confessed him, calling upon his name i.e. confessing him as Lord. So, were these men re-baptized? If we look to their master, John, for an answer, then we must conclude they were re-baptized in water by Paul (cf. Mark 3:14). Remember, many of John’s disciples were among the 5000 fed by Jesus in John 6 and followed him no more (John 6:66). They, like the Samaritans in Acts 8, needed to understand that John was the servant, and Jesus is Lord.
Luke tells us that these men, after Paul laid hands upon them immediately spoke in tongues and began to prophecy. This is the fourth occurrence in the book of Acts showing the visible falling of the Holy Spirit upon the disciples of Jesus. Acts 2 was the first, and it was a sign to the Jews that the Holy Spirit had come. Acts 8 is the second and it was a sign to the Samaritans and to the Jews that there should be no competition between brethren and the leadership was, indeed, at Jerusalem. The third is found in Acts 10 which was a sign to the Jews that God had received the gentiles just as they are. In other words, gentiles do not have to become Jews in order to worship the God of Abraham. The fourth and final occurrence of the falling of the Holy Spirit upon the disciples is found here in Ephesus where he fell upon John’s disciples, a sign to them that they should no longer follow the servant whose ministry was indeed inspired by God, but should follow the Lord who gave John the ministry that pointed to Jesus.
 William M Ramsay: “St. Paul The Traveler and Romans Citizen; chapter 12 “The Church in Asia” p.206 [revised and updated by Mark Wilson] ; Kregel Publications.