It is common in ordinary usage to find a variety of terms referring to the same thing. Sometimes there are inflexions or nuances between them, other times not.
Vertically, what discriminates between these sets?
ethical | unethical moral | immoral virtue | sin
It seems obvious that there are differences in the etymology if we consider the roots of these words, however, are they referring to different concepts, or, in fact, to the same concepts? Is there some subtle discrimination between them, perhaps vertically they are representing differing levels, although, I would argue that vertically there is no grey between them? i.e. if it is ethical it is moral and it is a virtue, if it is unethical it is immoral and it is sin. The basis for this argument is, if it is not sinning then, how can it be unethical?
Is the word selection, in fact, more evidence of the world-view or position of the word user than it is in discriminating between concepts? I conceptualise, for example, that the use of ethical and unethical allows one to discuss concepts of good and bad without needing any anchoring thought to concepts of a benevolent God. I would like to say that moral refers to a consistency with the outcomes of a story used for teaching, but, I do not know the words' full history.
I do not suppose even momentarily that this is strictly a question of language and usage but, that it requires thought. Although, I do intend to later ask the same question of EL&U.SE for a different set of views.