Jesus answered him, "Are you the teacher of Israel, and don't understand these things?
Greater importance attaches to John's baptism than is usually supposed. Jesus submitted to that baptism, as did (presumably) all the apostles, for it is inconceivable that the disciples of Jesus would have refused a baptism to which Jesus himself submitted.  Also, those disciples baptized others during John's ministry; and they could not have done this without themselves accepting it and obeying it.  Though called the baptism of John, it was actually God's baptism administered by John.  Also, for a season, it was also administered by Jesus through his apostles.  It was mandatory for all Israel, even for the priests and Pharisees; and it was the only baptism in force until Pentecost.  With Pentecost and the preaching of the Great Commission, John's baptism was supplanted by that of the commission; but it was valid until then.  The function of John's baptism was exactly like that of the great commission in the particulars of its being by immersion and its being the separator between the true Israel of God and the hardened secular Israel with which the true Israel was commingled until Pentecost.