When Jesus saw their faith, he said to the paralyzed man, “Son, your sins are forgiven.”
Now some teachers of the law were sitting there, thinking to themselves, “Why does this fellow talk like that? He’s blaspheming! Who can forgive sins but God alone?” Immediately Jesus knew in his spirit that this was what they were thinking in their hearts, and he said to them, “Why are you thinking these things? Which is easier: to say to this paralyzed man, ‘Your sins are forgiven,’ or to say, ‘Get up, take your mat and walk’? But I want you to know that the Son of Man has authority on earth to forgive sins.” So he said to the man, “I tell you, get up, take your mat and go home.” He got up, took his mat and walked out in full view of them all.
This amazed everyone and they praised God, saying, “We have never seen anything like this!”

--Parallel verses:
‭‭Matthew‬ ‭3‬:‭1-‭3‬
“In those days John the Baptist came, preaching in the wilderness of Judea and saying, “Repent, for the kingdom of heaven has come near.” This is he who was spoken of through the prophet Isaiah: “A voice of one calling in the wilderness, ‘Prepare the way for the Lord, make straight paths for him.’ ”

As I read this passage I ask, why does John Mark write (and likely Peter tell) about this specific miracle here? Why was it so important?

I think it is found more clearly in its correlation to John the Baptist. John preached, as we see in our cross-reference, repentance from sin. He wanted people to be seeking holiness, not compromising in life and living by comparison to others. He also preached that he was preparing the way for one greater.

Jesus came not to override John’s ministry, but to act as the fulfillment of it. John did not have the ability to forgive sins because he was not God. Jesus did because he was, at once, fully God and fully man. This is a mystery and it is also true. This passage in specific is evidence of his Godly state. God the Father was one with him and so was the Holy Spirit. The Trinity was alive and well on this day.

Jesus cared for us from the heart of God. He healed and rescued and saved from bad situations on earth. But he also came to forgive our sins and save us spiritually and eternally. He here announces this ministry and proclaims to all present that he IS GOD and does have the power to save!

At the same time, he heals a man paralyzed from birth and honors his faithful friends above everyone else. Those who thought they could measure up to God’s righteousness standards on their own — like the Pharisees and teachers of the law, or maybe like the ordinary people there — were shown the way by those who had incredible mercy and strength for this crippled man.

Lord, you call us to champion the causes of justice and mercy for those who cannot fight for themselves. You love the orphan, the widow, the invalid and the hurting. And you call me into spiritual battle in this world to help them too. I can’t do this in my own power and must take your lead. But where you do lead, I confidently go! No matter the obstacles or challenge — you are strong and mighty to save and victorious in the battle.