John was the forerunner to Christ, Water baptism was brought in as a commandment from God through John the baptizer, John baptized for repentance for remission of sins, but it took the blood of Christ which when John preached in the wilderness had not yet happened, therefore since Pentecost it required the teachings of Jesus, see Acts 19 where Paul re-baptized 12 that were baptized by John but never taught Jesus.
Acts 19:1-5 (NKJV)
[SUP]1 [/SUP]And it happened, while Apollos was at Corinth, that Paul, having passed through the upper regions, came to Ephesus. And finding some disciples [SUP]2 [/SUP]he said to them, "Did you receive the Holy Spirit when you believed?" So they said to him, "We have not so much as heard whether there is a Holy Spirit." [SUP]3 [/SUP]And he said to them, "Into what then were you baptized?" So they said, "Into John's baptism." [SUP]4 [/SUP]Then Paul said, "John indeed baptized with a baptism of repentance, saying to the people that they should believe on Him who would come after him, that is, on Christ Jesus." [SUP]5[/SUP]When they heard this, they were baptized in the name of the Lord Jesus.