The scribes and Pharisees heard a man claim to forgive sins, something they knew belonged to God alone. To them this was blasphemy. Barnes explains that blasphemy here means "to attempt to do or say a thing which belongs to him alone, or which he only can do." Their first question attacks Jesus' person ("Who is this?"); their second states the principle behind their charge. Matthew Henry notes that these men had come and sat by "as spectators, censors, and spies," not as learners. Their reasoning about God was right; their verdict on Jesus was not.

Jesus perceived their thoughts and answered with two questions: "What reason ye in your hearts?" and "Whether is easier, to say, Thy sins be forgiven thee; or to say, Rise up and walk?" (Luke 5:22-23). Then He said, "that ye may know that the Son of man hath power upon earth to forgive sins," and told the man to arise and go home (Luke 5:24). The man "rose up before them" and went home "glorifying God," and "they were all amazed, and they glorified God" (Luke 5:25-26). Matthew Henry sums up Jesus' reply: "'I will prove,' saith Christ, 'that I can forgive sins.'"

The KJV says they "began to reason." The Greek verb is dialogizomai, which Thayer defines as to reason, to "revolve in one's mind, deliberate." Jesus uses the same verb when He asks, "What reason ye in your hearts?" (Luke 5:22).

These critics were not a few local men. Luke says Pharisees and doctors of the law had come "out of every town of Galilee, and Judaea, and Jerusalem" (Luke 5:17). Barnes notes that to blaspheme God properly means "to speak of him unjustly, to ascribe to him acts and attributes which he does not possess," and here it means taking for oneself what only God can do.

The second question is true: only God can forgive sins. That leaves only two choices about Jesus. Either He was speaking blasphemy, or He was doing what only God can do. Jesus did not deny their principle. He proved His authority by healing the man so "that ye may know" (Luke 5:24).

Luke returns to this question later. At a Pharisee's table, after Jesus tells a sinful woman "Thy sins are forgiven," the guests ask, "Who is this that forgiveth sins also?" (Luke 7:48-49). The question "Who is this?" runs through Luke's Gospel, and Luke wants readers to answer it.