Matthew 9:6

But that ye may know that the Son of man hath authority on earth to forgive sins (then saith he to the sick of the palsy), Arise, and take up thy bed, and go unto thy house.

But that ye may know ... is equivalent to saying men could NOT KNOW Jesus' power to forgive sins without such a demonstration of his power. Now, if it is allowed that the Christ himself could not cause people to know of his power to forgive sins without the accompanying power to heal the body, how much more is it certain that people should never expect to have their claims to powers of absolution accepted without a similar demonstration on their part? Jesus' handling of this entire case shows that the power to forgive sins pertains to God alone and that only divine power can accomplish it. Here Christ places the absolution of sins on parity with performing a miracle, affirming in fact that one is as easily done as the other. What sophistry, then, must be attributed to those who "pretend" to do one but cannot even pretend to do the other! A clear understanding of these words of Christ would prohibit the unwarranted assumption of authority by those who make it their business to forgive the sins of other people!