Mark 2:7

He blasphemeth (blasphmei). This is the unspoken charge in their hearts which Jesus read like an open book. The correct text here has this verb. They justify the charge with the conviction that God alone has the power (dunatai) to forgive sins. The word blasphmew means injurious speech or slander. It was, they held, blasphemy for Jesus to assume this divine prerogative. Their logic was correct. The only flaw in it was the possibility that Jesus held a peculiar relation to God which justified his claim. So the two forces clash here as now on the deity of Christ Jesus. Knowing full well that he had exercised the prerogative of God in forgiving the man's sins he proceeds to justify his claim by healing the man.