I know you weren't trying to demean me.
The whole idea of karma itself is what goes around comes around- so naturally someone believing in karma will believe it was just, regardless of the particular 'victim'. Yet also, the view of how karma works varies- does karma just work off your physical actions? Even if you think so, physical actions are just the manifestations of thought. (Neurons transferring info for all the science folk) So therefore, all action is simply thought. Now, does anyone truly know the thoughts of another? If you cannot say for certain, then you simply do not know. So while karma and the such cannot be completely proven by science and such at this time- it certainly cannot be proven wrong either.
Wouldn't compare my beliefs to the Judeo-Christian concept of sin, though I could see how you might have thought that. The concept of 'sin' is created by the brain. The brain is not I, though it is mine to use. The concept of a sin is created by the brain, in it's attempt to decode what it is experiencing. The brain likes to label everything so it can file it away. In Judeo-Christian beliefs, one commits a sin, the brain categorizes it as a sin, then the person inflicts themselves with guilt and pain because of how it is perceived. At this point, not only will they reap karma from the 'sin', but they will reap the karma from the self inflicted guilt and pain. I think most of us have experienced the effect from a negative person coming into the room, how could self affliction of that be good at all? The idea of 'asking for forgiveness' as well just carries on the emotional destructive thoughts. I think it is much more beneficial to just accept how things are, accept the repercussions, and actively seek to avoid falling into the same holes.
I have a lot of respect for you email- the path which you choose to achieve wisdom is your own. Your morality and good nature have us on the same side anyways- doesn't matter the method personally preferred.
Study the laws of nature, apply them to your life.