Now those who were sent were from the Pharisees, they asked him saying, “Why then do you baptize if you are not the Christ, nor Elijah, nor the Prophet?” John answered them, saying, “I baptize with water, but there stands One among you whom you do not know. It is He who, coming after me, is preferred before me, whose sandal strap I am not worthy to loose.” These things were done in Bethabara beyond the Jordan, where John was baptizing. (vv.24-28)
Here we see that the Pharisees wondered about John’s authority to baptize, if he was not actually one of the prophesied ones they had in mind here in our text. Yet John’s work of baptizing perfectly suited his calling. John’s baptism by water demonstrated the humble willingness to repent, be cleansed, and prepare for the coming Messiah. Yet John’s baptism gave nothing to help someone keep clean. John explained to the religious leaders that he was not the focus of his work, but the One who was already among them. John’s work was to prepare the way for the One preferred before him.
John further described his position in relation to the One who was currently among them as, "Whose sandal strap I am not worthy to loose." To untie the strap of a sandal (before foot washing) was duty of the lowest slave in the house. This was even considered “too low” for a Rabbi to expect one of his disciples to perform. John's statement here took the focus off himself and showed his preference to the One.
The next day John saw Jesus coming toward him, and said, “Behold! The Lamb of God who takes away the sin of the world!” (v.26). John didn’t present Jesus as a great moral example or a great teacher of holiness and love. He proclaimed Jesus as the sacrifice for sin. It wasn’t “Behold the great example” or “Behold the great teacher” – it was Behold, the Lamb of God who takes away the sin of the world. He used ‘the lamb’ as the symbol of sacrifice in general. In this one sentence, John the Baptist summarized the greatest work of Jesus: to deal with the sin problem afflicting the human race.
The Truth: "For God sent not His Son into the world to condemn the world, but that the world through Him might be saved." (John 3:17)