Just to change up the discussion somewhat and perhaps clarify my position somewhat as well, the problem, as I see it, is that the concept of Soul and all the side issues around it is very limiting. Such concepts become too rigid resulting in Dogma and relying on an Authoritarian acceptance of Good/Evil being what the Deity(in most cases) proclaims it is. There is no need for clarification or any kind of explanation, it just is because it is what the Authority proclaims it is.
That's not to say that a Secular/Humanist/Atheist(one, a combination, or all) Construct can't fall into that same trap, but the vast majority of people have fallen into that trap through Religion based Metaphysical Philosophies. At this point in History anyway. Good/Evil need to be separated from Ancient Constructs in order to remain relevant. Fortunately, to some extent they have, however, the resurgence of Ancient Religions is troubling. When I speak of that I'm discussing mostly the 3 Abrahamic philosophies, Judaism, Christianity, and Islam, the ones I'm most familiar with. Most people with these 3 are mostly Traditionalists, by that I mean they are rather benign in the sense that they observe certain traditions that have little consequence(celebrations such as Christmas, Hannukah(sp), Ramadan for eg). Yet in all 3 there have been disturbing growth in Fundamentalist elements which dredge up practices that are not benign and are clearly harmful if not outright dangerous. These are people who would, given the opportunity, reverse our understanding of Good/Evil and go even beyond that to reverse our understanding of Science.
This is why these discussions always raise my cackles. I'm not saying that these Ancient Philosophers/"Prophets"/Founders were "Evil", in fact I'm sure at the time they were very admirable and deserving of the praise/position in History given to them. However, clearly, despite how revolutionary their ideas were at the time, they were simply unable to grasp how far their Concepts of Good/Evil could be or should be taken. I really don't blame them for that, it is always difficult to foresee such things given the limited scope one has at any given point in time. That said, it is foolish for us to limit ourselves by their limited scope and indeed to accept their scope as the final authority on Morality and/or Good/Evil. At best, IMO, one could argue that their views are a good starting point to view such complex subjects, but I think there are also some serious flaws in their thinking, again as a consequence of their limited view.