[Bêthberry]

I wonder, is sin an at all appropriate word to use about Middle-earth?

There is, after all, no "Fall" in the Legendarium--Tolkien said he hesitated to incorporate one so as to avoid the possibility of parody-- such as that in Genesis, and LotR appears to have a natural form of religion, without ritual, forms, churches and priests.

Without 'original sin' can there be any 'sin'? Note, I'm not saying there isn't error and evil, just that the connotations of 'sin' might be too Primary World for this sub-created world.