John 1:23-28 — He said, I am the voice of one crying in the wilderness, Make straight the way of the Lord, as said the prophet Esaias.
And they which were sent were of the Pharisees.
And they asked him, and said unto him, Why baptizest thou then, if thou be not that Christ, nor Elias, neither that prophet?
John answered them, saying, I baptize with water: but there standeth one among you, whom ye know not.
He it is, who coming after me is preferred before me, whose shoe's latchet I am not worthy to unloose.
These things were done in Bethabara beyond Jordan, where John was baptizing.
Quote from Isaiah 40:3— The voice of him that crieth in the wilderness, Prepare ye the way of the Lord, make straight in the desert a highway for our God. This is a prophecy of Christ's first and second coming. The Lord is a highway for God.
John heralds Christ, but he is only a voice. Again, his humility shows.
in the wilderness (the spiritual barrenness of Israel) — outside the dead temple and religious system
The Pharisees were big on rituals. They wanted to know what authority John had to baptize. Baptism expressed repentance. The Jordan River (lit. "descending) is a type of death. To be baptized meant an admittanced that death was deserved.
Neither John's kingdom message or his baptism has anything to do with the church.
Prior to this, baptism had been for Gentiles, a purification rite for converting to Judaism. For I will take you from among the heathen, and gather you out of all countries, and will bring you into your own land. Then will I sprinkle clean water upon you, and ye shall be clean: from all your filthiness, and from all your idols, will I cleanse you (Ezekiel 36:24-25). But John was baptizing Jews!
John administered repentance; Jesus provided a new heart and spirit.
When John spoke of Christ, there is no indication the Pharisees responded.
shoe lachet — untieing a sandal, the lowest of tasks
Bethabara — House of Passage — probably the same place where Joshua crossed the Jordan into the Promised Land. Now John was preparing passage into a new kingdom.