1 And again he entered into Capernaum after some days; and it was noised that he was in the house.
2 And straightway many were gathered together, insomuch that there was no room to receive them, no, not so much as about the door: and he preached the word unto them.
Crowds following Jesus is a reoccuring theme of Mark.
3 And they come unto him, bringing one sick of the palsy, which was borne of four.
4 And when they could not come nigh unto him for the press, they uncovered the roof where he was: and when they had broken it up, they let down the bed wherein the sick of the palsy lay.
So picture this, four guys are lugging a paralysed man to see Jesus. They couldn't get near Jesus because of the crowds but they can get to the house. Somehow, they get this poor man on the roof. Either they happened to be carrying rope or luckily found some. Then the men have to break the roof up so unless they used their bare hands they also brought tools. Finally, they dangle the paralysed man through the roof to the room where Jesus was preaching.
5 When Jesus saw their faith, he said unto the sick of the palsy, Son, thy sins be forgiven thee.
Sin causes illness. Demons cause illness.
6 But there was certain of the scribes sitting there, and reasoning in their hearts,
Again with the scribes.
7 Why doth this man thus speak blasphemies? who can forgive sins but God only?
8And immediately when Jesus perceived in his spirit that they so reasoned within themselves, he said unto them, Why reason ye these things in your hearts?
9 Whether is it easier to say to the sick of the palsy, Thy sins be forgiven thee; or to say, Arise, and take up thy bed, and walk?
Only God can forgive sins and only God knows men's hearts.
Jesus uses a Cynic technique to turn the tables on his challengers and answers their question with a question. This answer does not address the scribes question. Who cares which one is easier to say?
10 But that ye may know that the Son of man hath power on earth to forgive sins, (he saith to the sick of the palsy,)
This may be an aside to the reader, not the words of Jesus. Mark calls Jesus the Son of man, another of those loaded terms. It can mean human being or be used as a messianic title. Ezekel uses the term frequently and of course " And behold, One like the Son of Man..." found in Daniel.
11 I say unto thee, Arise, and take up thy bed, and go thy way into thine house.
12 And immediately he arose, took up the bed, and went forth before them all; insomuch that they were all amazed, and glorified God, saying, We never saw it on this fashion.
More amazed crowds, another Markian theme.