[Holbytlass]

I don't see it as so much aligned with religion as just the way things are. All things come to an end..places, kingdoms, races and so forth. I suppose that's part of some scientific theory I couldn't name.
I also see it as Alatar pointed out that humans do tend to look back on things either in memory or stories (ie, history) with rose-colored glasses. Romanticizing the good and not dwelling on the bad parts.
In essence Tolkien did have to tie this story in with true history down to real life now. He being the author could (and did) write people and places as grander and better than the state of things he was living in his own life.