Jesus was a humble person (Matt 11:28–30), but the claims that He has the power to forgive sins were unprecedented and breathtaking. He not only declared or assured people that their sins were forgiven, but He forgave them. This is the kind of authority only God possesses. The Jews knew very well that in the end only God has the authority to forgive sins. Nevertheless, Jesus forgave sins and proved that He has the right and the authority to do so by performing a miracle.
And when Jesus saw their faith, he said to the paralytic, “Son, your sins are forgiven.” Now some of the scribes were sitting there, questioning in their hearts, “Why does this man speak like that? He is blaspheming! Who can forgive sins but God alone?” And immediately Jesus, perceiving in his spirit that they thus questioned within themselves, said to them, “Why do you question these things in your hearts? Which is easier, to say to the paralytic, ‘Your sins are forgiven,’ or to say, ‘Rise, take up your bed and walk’? But that you may know that the Son of Man has authority on earth to forgive sins”—he said to the paralytic—”I say to you, rise, pick up your bed, and go home.” (Mark 2:5–11, ESV)
Jesus claimed God’s property as His property. He talked about God’s angels (Luke 12:8–9; 15:10; Rev 3:5) as His angels (Matt 13:41). Jesus has angels at His disposal, He could appeal to the Father, and the Father would at once put at His disposal more than twelve legions of angels (Matt 26:53). Jesus has a kingdom of God or the kingdom of heaven (Matt 12:28; 19:14), therefore, He can talk about “my kingdom” (Luke 22:29), which was not from this world (John 18:36). God’s elect people (Mark 13:20) are Jesus’ elect (Matt 24:31).