Jesus answered him, "Let it be so now,
for thus it is fitting for us to fulfill all righteousness"
Jesus comes to John the Baptist as one of the many people who came to John to be baptized. John objected, "I need to be baptized by you, and do you come to me?" (3:14). John knew that he was standing in the presence of the Messiah. And he knew his place in the pecking order.
Jesus shows Himself to be a condescending Lord. Jesus condescends to a place of submission even to John. This is the humility that St. Paul encourages us to imitate (Philippians 2:5). Jesus relinquishes His rights for this moment so that righteousness might be fulfilled.
What does it mean "to fulfill all righteousness"? Jesus submitted to a baptism of repentance so that His righteousness might wash off of Him. When Jesus was baptized, He had no sins to confess and repent. When you and I entered the waters of Baptism, our sins were washed away. They were washed away because the righteousness that washed off Him in the Baptism by John is washed onto us. We come out of Baptism sinless not because we've done some great act. We come out sinless because His righteousness has now been given to us.
Jesus was baptized so that He could fulfill all righteousness. That righteousness is the same that Abraham had so many centuries ago: "And [Abraham] believed the Lord, and He counted it to him as righteousness" (Genesis 15:6). Your faith that believes that your Baptism has washed away your sins is counted by God as righteousness. Righteousness has been fulfilled for you in Jesus' Baptism. Amen.