I started writing an answer to John's question in response to the post Setting the debt clock to zero, but it got too long for a quick reply. So here's a more considered one.
The question John posed was:
'Cancelled debt through forgiveness is at the heart of the Christian good news. Of concern to me is the oft-encountered notion that Jesus paid the debt owed to God, as if a third party could somehow repay the moral debt of another. Any thoughts?'
Good question. So how would I answer that one? Can we really talk about moral debt as if it's some kind of commodity that one person can accumulate on behalf of someone else, let alone the consideration of whether the New Testament ever says that Jesus paid our debt.
Well I've a short answer and a longer one. My short answer would be to say that just as in Christ God was relating to humanity, so also Christ was, in himself, relating humanity to God. God was in Christ reconciling the world to himself, and in Christ the believer is crucified and buried and becomes the righteousness of God (amongst a whole host of other amazing results). Jesus offers himself to God not just as an individual man, or even just as the Son of God, but as the second Adam - he wraps up the whole of humanity in himself. So on that basis I would say that in Christ humanity pays its debt to God.
Mind you, if I only had 10 minutes on the street to explain the Gospel using this image I would probably say Jesus paid our debt without worrying too much about the niceties. Why am I OK with that? Well two general principles help me here.
First, the New Testament is far more concerned with the effect of of Jesus's life, death, and resurrection, and less interested in the mechanics. To take an example, Jesus describes his mission as payment of a ransom, but never says to whom the ransom is paid. To ask the question misses the point. The ransom image reminds us we are powerless to free ourselves and someone else needs to intervene. It also implies that bringing about that freedom will be costly for someone else. The cross shows how costly and for whom rather than to whom. That's the point of the image.
Secondly, it helps me to remember that the explanation of Jesus's ministry comes from missionaries rather than philosophers. Jesus taught his apostles to explain the faith more through compelling images, and affirming historical realities than propositions. Freedom is won, enemies are reconciled, slaves are freed, lost children find their way home, a sacrifice is made to end all sacrifices, the downtrodden and oppressed inherit riches beyond measure to name but a few. These images are a call to a new identity, a new lifestyle, a new orientation towards God, and immersion in a new community. They are based on historical realities that take effect first in the real lives we live now. Jesus lived a life among poor people, engaged with the issues of his day, died a vicious death, but now lives again in a real tangible, touchable body. They are to some extent designed to explain, but are more focused on bringing about a change of motivation. And yes, whilst repentance demands thought (it is a change if mind) it's one that leads to a change in action.
So let's go back to the ransom idea. Redemption doesn't mean I'm freed to do what I like, but rather that I have a new master. Only this master gives me the status of a son and becomes my Father. I don't go from one form of slavery to a more benign version of the same state. This is the freedom to be part of a new relationship, and a new community, that outside of Christ no freedman could ever imagine; it opens up a vast array of possibilities that a simple change of ownership could never begin to accommodate.
Some images are stronger on some of those aspects than others, none provides a complete picture within itself, and their variety helps us relate to different cultures. So I wouldn't talk to a Norwegian about debt (Norway has no national debt and living standards are universally high). Penal substitution (even when preached by missionaries who are wedded to it) makes little impact among the Japanese because their legal system, and ideas of dealing with criminality and maintaining social order are so different from Western cultures. The concept of sacrifice is alien in the west but still has powerful resonance in many third world cultures. Images of ransom, and of victory over oppressors may have far more impact in former communist bloc countries than the UK which has no national memory of invasion or oppression.
So there are my thoughts. Yours are welcome (!).

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