(20) When Jesus saw their faith, he said, “Friend, your sins are forgiven.”
(21) The Pharisees and the teachers of the law began thinking to themselves, “Who is this fellow who speaks blasphemy? Who can forgive sins but God alone?” (NIV)
There are those who believe that only God can forgive sins, but that is not true. For an explanation applicable to this verse, see Mark 2:7.