Philip baptizing in Samaria is another instance of the evolving ancient Jewish water ritual. It later began devolving under Paul the Apostle.
It had been re-implemented by Peter, but had not been practised by Jesus after God the Father inducted him into the new priesthood wherein he became the High Priest forever after the order of Melchisedek. (Hebrews 7)
Christ ceased submission to the Levitical priesthood, the very moment John the Baptist had had baptized his cousin from the tribe of Judah.
“But when they believed Philip preaching the things concerning the kingdom of God, and the name of Jesus Christ, they were baptized, both men and women”. … “Now when the apostles who were at Jerusalem heard that Samaria had received the word of God, they sent unto them Peter and John: Who, when they were come down, prayed for them, that they might receive the Holy Ghost: For as yet he was fallen upon none of them. Then laid they their hands on them, and they received the Holy Ghost.” (Acts 8:12; 14-17.)
Philip’s water rite did not regenerate the baptized.
Water was not the agent of rebirth.
Though Philip was an authorized emissary of the apostles, and filled with the Spirit. Peter and John did not re-baptize the Samaritans.
The Samaritans were converted by the righteousness-of-faith, endowed by the Spirit of Christ, which both regenerated them within, and baptized fire upon them.
Their own faith and water baptism was inadequate.
They, and the generations which followed, needed to realize man’s inability and incapability to access grace. In the presence of three men of God: Philip, Peter and John, came the final enlightening illumination of the waiting penitents.
http://bonitabiblemission.worthyofpraise.org/vexing-questio…baptism-7-of-9/
