The Baptism of John
The baptism of John was not Christian but Jewish, especially unto repentance. The only faith it had concerning the Messiah was that His coming was close at hand. They who confessed and repented of their sins and were baptized by John were thus obedient to his call to "prepare the way of the Lord."
While Apollos was at Corinth Paul finding certain disciples asked them, "Have ye received the Holy Ghost?" They were unto John's baptism. Paul laid his hands on them. Apollos was instructed in the way of the Lord, knowing only the baptism of John. Aquila and Priscila heard and expounded the way of God more perfectly. Paul is going to meet some of these "John" disciples on his way to Ephesus. The only message the people heard was "repent and be baptized" to prepare for the way of the Lord. They repented, but needed to learn of the baptism of the Holy Ghost. There at Ephesus, Paul introduced them to the second half of John's message - receive the Lamb of God. As did Apollos, they supposed John's baptism to be FROM evil only, they needed to know what it meant to turn TO the One coming after him. It was not merely to repent but to get ready to receive.
John baptized in the Jordan.
[291, Acts, BD]