This is a fascinating question. Thank you to HareBrain for pointing out Tolkien's Letter 210.
This is simply my own take on it: The great concern of Tolkien was power. Power corrupts. The ring was sought by the great evil power, Sauron, but could only be destroyed by someone without power, the weak hobbit Frodo. Gandalf observes this explicitly in the Council, that it is the only hope of "getting under Sauron's radar". The temptation to power is why Gandalf will not handle the ring. So I would say this is the story, though I'm not sure that was what Tolkien was getting at in Letter 210, the human story of how weakness defeats power. Of course, in the story Frodo is really a failure. He doesn't destroy the ring, he succumbs to its power, and needs to be saved by outside forces. When Frodo is entirely lost and defeated, then the eagles raise him up from death (they also snatched Gandalf from captivity). This seems to be to be a kind of "deus ex machina," which is usually condemned as a very poor plot device. However - I think - in the LOTR it is used as it should be, because in reality human beings fail and need rescue. I must admit personally that I shed a tear when I read "The eagles are coming! The eagles are coming!" because it's the climax of the story. and it is a "whopping good story!!! "
Tolkien was a Christian, and while he said that his works were not a preachment (as C. S. Lewis' often are), nonetheless it is the world in which he lives and the language that he uses. St. Paul says in 1 Corinthians 1, 27, "the weak things of the world hath God chosen that he may confound the strong," and that's what the whole LOTR is about. Tolkien uses the eagles to snatch out of desperate circumstances, and this theme of God snatching people from dire straits is a frequent theme in the Old Testament (for example, Exodus 19, 4 and Isaiah 40, 31). Tolkien certainly knew of these passages.
This is simply my own take on it: The great concern of Tolkien was power. Power corrupts. The ring was sought by the great evil power, Sauron, but could only be destroyed by someone without power, the weak hobbit Frodo. Gandalf observes this explicitly in the Council, that it is the only hope of "getting under Sauron's radar". The temptation to power is why Gandalf will not handle the ring. So I would say this is the story, though I'm not sure that was what Tolkien was getting at in Letter 210, the human story of how weakness defeats power. Of course, in the story Frodo is really a failure. He doesn't destroy the ring, he succumbs to its power, and needs to be saved by outside forces. When Frodo is entirely lost and defeated, then the eagles raise him up from death (they also snatched Gandalf from captivity). This seems to be to be a kind of "deus ex machina," which is usually condemned as a very poor plot device. However - I think - in the LOTR it is used as it should be, because in reality human beings fail and need rescue. I must admit personally that I shed a tear when I read "The eagles are coming! The eagles are coming!" because it's the climax of the story. and it is a "whopping good story!!! "
Tolkien was a Christian, and while he said that his works were not a preachment (as C. S. Lewis' often are), nonetheless it is the world in which he lives and the language that he uses. St. Paul says in 1 Corinthians 1, 27, "the weak things of the world hath God chosen that he may confound the strong," and that's what the whole LOTR is about. Tolkien uses the eagles to snatch out of desperate circumstances, and this theme of God snatching people from dire straits is a frequent theme in the Old Testament (for example, Exodus 19, 4 and Isaiah 40, 31). Tolkien certainly knew of these passages.