From the Torah the Jews had learned about purification, ablutions and a sort of baptism. Ablutions were a cleansing from moral filth, whereas baptism proper was specifically for the purification of non-Jews, because they regarded the nations as unclean. Anyway, accepting baptism was a sign of humility and of joining God's people.
This explains why the delegates from Jerusalem were perplexed. "Why are you calling believers to repent, those who are circumcised and fully established in the covenant? Do you regard us as lacking in holiness and think that we are lost in God's anger, we the responsible leaders of our nation?"
John's baptism was a stumbling block to "pious" folk. It split the people into two groups. The first group were those purified by the baptism of repentance. They were to welcome Christ as a selected crowd ready to meet their Lord. The second group rejected the baptism of repentance, feeling they were fit to welcome the Christ. They assumed that his coming was to be for political or legalistic ends.
Probably the evangelist John, himself, was present at this official examination. The discussion deeply touched him, especially the questions of the delegates to the Baptist, for with them they elicited his confession that he was neither the Christ, nor Elijah nor the promised prophet. With this response they disgraced him, revealing that he was a nobody.
The Baptist, knowing what was to be done, belittled himself and said with a smile, "You are right, I am nobody important. I baptize only with water, without magic or power. All I do is symbolic, pointing to the Coming One."
Then the Baptist in his attire of camel fur stood up and called out in a loud voice to the leaders of the delegation and to the crowds, "You are all blind. You fail to notice the historic event happening in your midst. You examine me, who is but a minor figure. But look, the Christ has come. He is here in the midst of this crowd of penitents. I, John the Baptist, have no power to do anything. I have but one service to fulfill. I am a voice, and the Holy Spirit informed me about the Lord who is coming right now. He is here. Today is the day of Salvation. Repent quickly, for the last moments are passing by."
At this announcement the crowds were awe-struck. They had gathered with the aim in mind to welcome the Christ. But he had already arrived, and they had neither noticed his coming nor seen him. They were deeply perplexed, looking at each other in astonishment.
Then the Baptist uttered his famous description of Christ in a testimony which is more explicit than what the writer of the gospel had already indirectly mentioned in verse 15, "He who is coming after me was before me." With this the Baptist revealed the eternity of Christ and at the same time his presence among men. He made it clear that outwardly the Christ was a normal human being in their midst, unrecognized, without halo, elaborate clothing or flaming eyes. He was just like everyone else, not standing out in any way. But in his true nature he was totally different from others: A being before all ages, heavenly and divine, standing in their midst in all simplicity.
The Baptist confessed his unworthiness to be Christ's servant. The custom of the time was, that when guests were received in any home, a servant would wash their feet with water. Seeing that Jesus had come to the crowds, the Baptist regarded himself unfit even to loose the latchet of Jesus' shoes in order to wash his feet.
These words stirred the crowds. They questioned one another, "Who is this stranger nearby? How can the Lord be a commoner? And why does the great Baptist say that he is unfit to loose the latchet of his shoes?" The delegates from Jerusalem maybe sneered on hearing the Baptist, as if to say, "This squalid Baptist is a trickster!" So they left. Probably some of the Baptist's followers followed their example, thinking that Christ would appear in their capital Jerusalem in radiance and majesty and not as an unknown, simple person in the wilderness. Thus they missed a unique chance to meet with God's Christ.
These events took place on the east bank of the Jordan, lying beyond the Sanhedrin's authority, in an area under Herod Antipas' rule. The delegates therefore were not able to arrest the Baptist and take him with them to be judged in Jerusalem.