Acts 19:4

4 "That explains it," said Paul. "John preached a baptism of radical life-change so that people would be ready to receive the One coming after him, who turned out to be Jesus. If you've been baptized in John's baptism, you're ready now for the real thing, for Jesus."

Acts 19:4 Meaning and Commentary

Acts 19:4

Then said Paul
In reply to their answer, understanding them that they were baptized by John, he takes it up, and gives an account of John's baptism: showing how agreeable it was, and that it was the same baptism with the baptism of Christ, being administered in his name:

John verily baptized with the baptism of repentance;
which required repentance antecedent to it, and was a fruit and effect, and so an evidence of it:

saying unto the people;
the people of the Jews, the common people, the multitude that attended on his ministry:

that they should believe on him, which should come after him,
that is, on Jesus Christ; so that he preached faith in Christ, as well as repentance towards God; and made the one as well as the other a necessary prerequisite unto baptism; which shows, that his baptism and Christian baptism are the same.

Acts 19:4 In-Context

2 The first thing he said was, "Did you receive the Holy Spirit when you believed? Did you take God into your mind only, or did you also embrace him with your heart? Did he get inside you?" "We've never even heard of that - a Holy Spirit? God within us?"
3 "How were you baptized, then?" asked Paul. "In John's baptism."
4 "That explains it," said Paul. "John preached a baptism of radical life-change so that people would be ready to receive the One coming after him, who turned out to be Jesus. If you've been baptized in John's baptism, you're ready now for the real thing, for Jesus."
5 And they were. As soon as they heard of it, they were baptized in the name of the Master Jesus.
6 Paul put his hands on their heads and the Holy Spirit entered them. From that moment on, they were praising God in tongues and talking about God's actions.