... continued from before
A final issue raised by Jesus' healing of the paralytic in Mark 2 is the authority to forgive sins. Given the association between sin and sickness in their minds, perhaps these teachers of the law had the mindset that the paralytic's condition was God's judgment on him or his family for something he or they had done. In that sense, what authority did Jesus have to pronounce forgiveness if healing did not accompany? Perhaps in their minds, if God forgave the man, God would heal the man. Of course Jesus made his line of questioning moot when he went on to heal him.
We might leave the issue there if we did not find an intriguing charge by Jesus to his disciples in John 20. It is the evening of Easter Sunday. Jesus appears to ten of the disciples (minus Thomas). He breathes on them and invites them to receive the Holy Spirit, perhaps John's equivalent of the Day of Pentecost in Acts 2. Then comes Jesus' startling pronouncement: "If you forgive anyone’s sins, their sins are forgiven; if you do not forgive them, they are not forgiven."
This statement would not be shocking if Jesus were merely saying, "When you know I've forgiven someone, feel free to announce it to them." It then becomes an empty statement. "If you make it through the traffic light, you have made it through the traffic light." Yeah? So what?
What is shocking is that Jesus seems to be saying one or both of two things. First, someone may want to have their sins forgiven and I am giving you the authority to keep them from being forgiven. Secondly, there may be people who do not want their sins forgiven that you can forgive anyway. The first is problematic because it implies an unloving, unchristlike attitude to the point of causing someone's condemnation. The second is problematic because it implies that we can dispense out salvation to those who have not made an act of faith.
It would be nice if this were merely a statement about healing. Jesus would be giving the authority to heal and thus, by implication, to repair the consequences of sins in some situations. Surely at least we can take the statement that far. Jesus has given the church authority to administer discipline and, if you would, penance in consequence of sin. Penance is a sacrament in the catholic tradition that helps a person work through their guilt by doing some act of repentance. Afterward, that person's sin is considered forgiven.
While Protestants generally have strong reservations about such things, perhaps there are elements of such practices that are not only biblical but healthy. In my tradition, the Wesleyan tradition, we used to talk about doing restitution for a wrong you had done. In effect, it amounted to a kind of penance for a wrong you had done. You "made up" for something you had done by doing something.
The high Protestant traditions, especially the Lutheran tradition, has rightly suggested that we cannot earn God's forgiveness by any amount of "work" of this sort. That must remain our core theological position. Forgiveness for sins is given to all who genuinely seek God and repent, who turn in their hearts in a new direction. This is a matter between them and God into which no human can interfere. I cannot stop someone from coming to God and, ultimately, I cannot help someone come to God beyond a certain point if it is ultimately his or her choice.
But I can be a channel for them to feel God's forgiveness. Restitution and penance resonate with the human psyche, with the way we are built. We may not be able to "feel" forgiven without action of some sort. I'm reminded of a famous scene in an old movie called The Mission, where a notoriously wicked man cannot feel forgiven for killing his brother.  Although it is unnecessary, the priest finally charges him to carry a large load of armor on his back through the jungles of the Amazon.
At one point, he struggles to the top of a waterfall with the tremendous load on his back. He is almost to the top but then, in his weakness, is pulled back by the load. He is in danger of falling back down to his death. The priest comes and cuts the rope holding it and the weight falls to the bottom of the waterfall. Suddenly the man starts crying uncontrollably. The load is lifted. He feels forgiven.
As a Protestant, I do not believe that penance or restitution is necessary to have God's forgiveness for sins, nor do I believe that anyone can keep someone from forgiveness if he or she genuinely is seeking it from God. But I do believe that God has given the church the authority to discipline those who do wrong and that the church can require a person to do certain acts to demonstrate repentance and feel forgiveness. This authority has been abused in the past and is a sacred charge, but it is the best way for us to apply these striking words of John 20.
One additional word on this verse seems appropriate. There are times when we can experience doubt or uncertainty about God. Particularly in this day and age, there are many challenges to old ways of thinking that can confuse and cause doubt. Some are not bothered. They have the mixed blessing of not being troubled with ideas that don't fit the ideas with which they start out. 
However, most of us at some point have questions. A growing phenomenon today is when older saints in the church begin to have questions near the ends of their lives. Similarly, it is quite normal these days for those in their late twenties to experience serious questions about matters of faith.
In those instances, fellow believers can play a significant role in having faith for those who are doubting. I've heard of ministers having faith for older saints, even for former church leaders, on their death beds. And I've heard of younger believers having faith for fellow Christians questioning in their twenties. I remain firmly a Protestant in my sense that faith is a personal and individual matter. But perhaps we have also missed out on the role that the body of Christ can play as channels of God's grace and forgiveness to one another, as well as a means of grace through discipline.
 It's a mixed blessing because it is overwhelmingly unlikely that any one person starts out with all the right ideas. Those who are blissfully unchanged by any new thought are people who inevitably spend their lives in ignorance about many things.