Listen to Him

Matthew 3:13-17 (ESV)
Then Jesus came from Galilee to the Jordan to John, to be baptized by him. [14] John would have prevented him, saying, "I need to be baptized by you, and do you come to me?" [15] But Jesus answered him, "Let it be so now, for thus it is fitting for us to fulfill all righteousness." Then he consented. [16] And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; [17] and behold, a voice from heaven said, "This is my beloved Son, with whom I am well pleased."
This is where Jesus begins his ministry here. He begins by being baptized by John, a baptism that is for repentance. John knows Jesus has nothing for which to repent. John knows that he himself has things for which to repent. He thinks it would be better to subject himself to a baptism by Christ.
You can see John’s thought here. If John subjects himself to being baptized by Jesus, then the people will see that Jesus is greater than John, maybe they will even be tempted to follow Jesus and listen to him. But this would just perpetuate the law that kills. This would just make Jesus a greater John, not a messiah. This would signal that Jesus ministry would be one of more law.
So no, Jesus tells John, to fulfill all righteousness you baptize me. Jesus has bigger things in mind than preaching law. He wants to fulfill all righteousness. What happens here is Jesus repents, this is what John’s baptism was about. He repents, but of what? He repents of our sins. In other words, he as one of us, though sinless, takes responsibility for our sins. In repenting of sin, he takes responsibility for sin. Our sin becomes his burden. And the Father is so pleased with this, that as Jesus makes his way out of the water, that is as he climbs the riverbank, the heavens open the Spirit descends as a dove, and the father speaks. “This is my beloved Son, with whom I am well pleased.” The Father tells us to listen to his son, and his son has particular words to speak to us, “your sins are forgiven.”