When Jesus forgave the paralyzed man, he was forgiving the sins of a stranger; he was forgiving the man for harm he caused to others, not to Jesus himself.
And similarly for the immoral woman in Luke’s account. It could perhaps be supposed that he was familiar with her from another occasion, but not that she had caused him harm on that occasion. Jesus was, again, forgiving her for harm she had done to others, not personally to Jesus.
In these two separate events Jesus was acting as God Incarnate. The harm these two had done had in fact also been done to Jesus, as God incarnate. That’s why Jesus could forgive them, even though he had not humanly participated in whatever their sinful behavior had been.
But it goes without saying that we Christians are not God incarnate. Our privilege does not extend to the forgiveness of strangers. How could it, since we by definition have not been harmed by them?
The magnitude of the human privilege of extending divine forgiveness is staggering, but its scope is limited. It is limited to the forgiveness of those who have done us harm.
The Christian privilege of forgiving sins is not innate to them because of who they are – as it was innate to Christ – but rather an authority vested in them by virtue of something they have done, namely, committed their lives to the service of Christ.
A Christian’s authority may be thought of as something like the authority of a king’s ambassador. An ambassador’s authority exists within prescribed limits, prescribed applications. An ambassador may arrange treaties by the King’s vested authority, but an ambassador’s eldest child does not automatically become the next in line to the throne, should the king die. That privilege lies with the king’s oldest child, simply by virtue of who the child is.
So also, in the spiritual nature of things, a Christian does not suffer from the behavior of strangers, as Christ did. Christians, like non-Christians, suffer only from the harm done to themselves, and can forgive only that harm. To extend our image, Christians are the ambassadors of God’s forgiveness for the harms done to us, not the harms strangers do to each other.
None of this is to deny that we can be harmed as, so to say, collateral damage by those who are not targeting us directly. The mother suffering from wrongful harm inflicted on her child is a good example. But even in cases like these, the only harm the mother can forgive is the harm done to her, not the harm done to her child.
Our language obscures this spiritual truth. The mother might readily say to her child’s assailant: “I forgive you for what you did to my child.” But that has no bearing on the child’s own grievance. The primary debt created by that grievance is owed to the child, and that debt only the child can forgive. The mother’s forgiveness cancels only the debt owed to her, not the debt owed to her child.
And similarly for all other cases – many much more subtle that this one – of personal harm suffered from the maltreatment of others.