The mission is marked, at every turn, by danger. Bilbo and the dwarves confront hungry trolls, fierce orcs, wicked goblins, ferocious wolves, giant spiders, and eventually the mighty fire-breathing dragon himself. These fanciful characters signal the fact of serious evil at work in the world. Tolkien was a participant in the trench warfare of the First World War and thus experienced, at first hand, cruelty, violence, injustice, depravity, and mind-numbing fear. His Christian faith gave him the conviction that all of this evil was the result of sin, at both the human and super-human level. It also helped him to see that the whole point of life was to enter into the lists against evil, to find one's unique calling to battle wickedness and hence bring the world more into conformity with the reign of God.
What is particularly instructive in The Hobbit is the manner in which a Christian knight properly engages in the battle. At a key moment in the story, Gandalf suggests that while many think darkness is best opposed through exercises of great worldly power, in point of fact, it is most effectively countered through simple acts of kindness. This is, of course, nothing but Jesus' still deeply challenging teaching in the Sermon on the Mount that evil is properly resisted through love, non-violence, and forgiveness. The most striking example of this principle in action is Bilbo's refusal to kill the loathsome and dangerous Gollum when he has the chance. As readers of The Lord of the Rings know, Gollum would, despite himself, play the decisive role in the destruction of the ring. Had Bilbo indulged his violent instincts and put Gollum to death, the day would not have been saved. That evil is best engaged through pity is a deeply Christian and profoundly counter-intuitive insight.
At the climax of The Hobbit, the adventurers come face to face with Smaug, the dragon who, deep in the bowels of a great mountain, guards a pile of treasure absconded from the dwarves many years before. The beast knows every little bit of his horde: each coin, each goblet, each jewel and precious stone. To be sure, he cannot possibly use or benefit from any of it, but he wallows in it and protects it with his life. Tolkien refers to this weird obsession as "the dragon sickness," and he implies that it bedevils many people in contemporary society, those who know the value of everything and the worth of nothing. The Hobbit is a narrative spun by a serious Catholic who wants to communicate the still surprising ethics of the Gospel.