Imagine No Redemption

[Hookbill the Goomba]

I wish I could write a better response but computer troubles have tied my hands. And it is very difficult to type with tied hands.

The discussion of Radagast shows, I think, the main point of the topic; that there are so few examples of one turning from evil to good that we must discuss at length what constitutes turning to evil or back.
If you count the fight against Sauron as the ultimate 'good' and that anything that does not aid that to be therefore 'evil' I think there may be a case to be made. Though he does dip his toe into the waters of helping in the fight, Radagast generally stays out of the buisiness of helping. If he'd been more involved perhaps it would have gone smoother, therefore his lack of aid could be seen as inadvertently helping Sauron.
A sort of "if you are not for us then you are against us" situation.

Radagast's heart is in the right place, perhaps. His head may not be. Be does not turn to the dark side and so has nothing to repent of, unless his lack of full commitment to the mission counts against him.