What is the message of Matthew 9:5? Matthew 9:1-8 (NIV)
  1 Jesus stepped into a boat, crossed over and came to his own town. 2 Some men brought to him a paralyzed man, lying on a mat. When Jesus saw their faith, he said to the man, “Take heart, son; your sins are forgiven.”
   3 At this, some of the teachers of the law said to themselves, “This fellow is blaspheming!”
  
  4 Knowing their thoughts, Jesus said, “Why do you entertain evil thoughts in your hearts? 5 Which is easier: to say, ‘Your sins are forgiven,’ or to say, ‘Get up and walk’? 6 But I want you to know that the Son of Man has authority on earth to forgive sins.” So he said to the paralyzed man, “Get up, take your mat and go home.”  7 Then the man got up and went home.
  8 When the crowd saw this, they were filled with awe; and they praised God, who had given such authority to man.


What does  Matthew 9:5 mean?

Taken literally, it doesn't seem to make any sense at all. What is the verse trying to say?
Christ is using his ability to perform miracles as evidence that he is God, and therefore has the right and the ability to forgive sins.

He is saying, anyone can say "Your sins are forgiven," without any evidence that they have the authority to do so.  But only God can heal a paralytic.  So by performing such a miracle, Christ is proving that he has the authority of God both to heal and to forgive sin.