Failure and Punishment

[Raynor]

There is only one referrence in Tolkien's works on sins, that I know of, and even that favors Frodo:

Originally Posted by Footnote to Melkor / Morgoth, Myths Transformed, HoME X

Every finite creature must have some weakness: that is some inadequacy to deal with some situations. It is not sinful when not willed, and when the creature does his best (even if it is not what should be done) as he sees it - with the conscious intent of serving Eru.