What is the moral lesson of Lord of the Rings?

Answer 1

I read the books a long time ago, but the main moral I believe is that one should live life making sure greed does not consume it. The race of men is cast as the greedy, deceitful, power-seeking race. Because of men the ring was not destroyed thousands of years ago (Isildur), and their need for power is highlighted by the nine ringwraiths and Boromir's attempt to steal the ring from Frodo. On the other hand, the hobbits lives are that of simplicity and they are the "good" race. More importantly their way of life is advocated as the just as they live amongst themselves in peace without the thirst for power or greed. Of all the races, the hobbits lives maybe quaint in comparison, but they live in peace and avoid the problems that men, elves, and dwarves encounter.

Answer 2

There is none, Tolkien said so later in letters he wrote about The Hobbit and LotR books. Neither has a moral, they were not intended to be that kind of story.