The Redemption of Middle Earth and the "Collision of Evil"

In reading "Tolkien and the Nature of Evil," the idea behind how the ring was destroyed intrigued me. Scott A. Davison says that the destruction of Sauron-the major evil force in The Lord of the Rings-"resulted from the apparently coincidental collision of three evil impulses: Frodo's desire to keep the Ring, Gollum's desire to take it from Frodo, and Sauron's single-minded focus on world domination, made possible by his confidence that nobody would ever try to destroy the Ring (p.107)." While the destruction of the Ring seems to be the point around which the redemption of Middle Earth centers, it does not seems as straightforward to me as the redemption of Narnia.

In Narnia, Aslan is obviously the Christ figure. He offers the sacrifice of his flesh and blood to atone for Edmund's sin, as well as the sins of Narnia. Good is used to atone for evil.

The Lord of the Rings, however, puts a twist on this redemption. While Frodo definitely had good intentions for destroying the ring, he still gave in to the lure of its power. It was only because of his evil desire to keep the ring and Gollum's evil desire to take the ring from Frodo that the Ring was destroyed. Evil was used to redeem evil.

I can't help but wonder if this could be representative for how God works at times. God's purposes and plans are secure and will be carried out regardless of the choices we make. No matter how many times we fall to temptation, God can and will bring good out of evil. He can use experiences where we have made mistakes to teach us and to teach others. Perhaps what Tolkein was trying to convey was not a direct parallel to the crucifixion and redemption from sin ( giving salvation), but redemption from sinful choices (still resulting in God's good plan).