“But Jesus answered him, ‘Let it be so now, for thus it is fitting for us to fulfill all righteousness.’ ”
The reason God sent His Son into the world is to fulfill all righteousness for us, to do what we could not do. So here Jesus plunges Himself into our sins and soaks them up in His Baptism, so that in our Baptism we might be cleansed and renewed. The whole of Jesus’ life, everything He did and said, was one great offering to the Father in our stead to fulfill all righteousness for us. All our offerings back to our Lord are in thanksgiving for this one great, true offering.