the nature of sin

[Belacqua]

Morality relates to actions between people with harm/pleasure/benefit/etc. as vectors, and ethics is the codification of that, so yes. 'Sin' doesn't enter into it.

Laws are man-made codifications of behavior, so they exist as much as behavior  that has an impact on people's lives, so yes.

Thank you, this is much clearer to me now. (I wasn't clear on what you meant by "ontological existence," for example. Is there existence which isn't ontological?)

So if I'm reading you right, morality and ethics are about real-world behavior and consequences. 

It seems to me that the consequences of our actions are often concrete (e.g. people died because of his actions) but the morality of the consequence (e.g. it is bad to cause people's death) is in the minds of people. There is no way that a physicist could measure the badness of a consequence in an objective way -- it is bad because society agrees it's bad. And of course all of this is open-ended and subject to debate: to what extent the goal of morality is pleasure, for example, and when it is good to give up one's pleasure for moral reasons is a tricky issue. Perhaps there are situations in which we should behave a certain way and everyone would end up miserable anyway. 

But I think I see the point. Morality for you is about human real world consequences, whereas sin is based on divine dictates.

One is not like the other. 'Sin' is made up, without referrals, unlike what morality or laws do.
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Ultimately, 'sin' is about transgression against god(s) laws or 'divine' laws, whereas morality is about interaction between people.

Here, as always on this forum, I think you are arguing against the literalists, the TV evangelists, and people like that. Also perhaps against Drich, although I haven't read his posts closely. 

It is one view of how sin and divine law operate. It was certainly given a popular description by Hitchens, who described heaven as a kind of North Korea with God as its tyrannical law-giver. 

If this is the way some Christians see sin, then I agree it should be argued against. 

Naturally, it is not the view of Augustine, Aquinas, Dante, or any other major Christian thinker. For such people, God is the Good, and his Logos is the order and principles according to which the universe operates. Morality is when we act in accordance with those principles and aim for the Good of ourselves and everyone else, and sin is when we desire things that don't accord with the Good. The laws and aims are not laid down tyrannically or arbitrarily -- they are just the paths we need to aim for our own best outcome. Such a view is compatible with what you say about morality, in that it has positive outcomes for real people. It differs from your view, as far as I can tell, because it posits -- in the largest possible sense -- a universality that transcends local contingencies in mores. 

But experience shows that on this forum people only address the literalist view, and deny that the God of the theologians and philosophers has any consequence within Christianity.