Jesus already healed many illnesses in the same area (Mark 1:32–34). So why this reaction of amazement? The emphasis here lies not on what happened, but on how it happens. It is the first time that a healing opens a window on the forgiveness of all sins, that people had learnt to expect through John the Baptist. This healing shines as a mysterious promise.
After Jesus’ statement about forgiveness, the scribes thought it was blasphemy. Yet the healing immediately afterward shows that God does not punish Jesus for speaking about forgiveness, but that he continues to share in the powers of God to heal. When a power from above is in Jesus and leads to the recovery of the paralytic, it shows that God takes delight in the preceding words about forgiveness, even though it scared the unbelieving scribes.
God is at work in Israel: paralytics are healed after being forgiven and the Son of Man may do it all. That is why the people glorified God, even though they did not yet realize that the Father is one with Jesus, the Son.1
12 And he rose and immediately picked up his bed and went out before them all, so that they were all amazed and glorified God, saying, “We never saw anything like this!”