It's been a month since The Dark Knight came out and it's still leading the pack at theaters. We're not talking blockbuster any more, we're talking box-office phenom. When this many people come in past the first couple of weekends, it means they're going back again and telling their friends too.

There are plenty of good reasons why. To start with, Ledger's acting in this movie is every bit as good as everyone says it is. And if his portrayal of the Joker weren't so compelling, everyone would be talking about how strong the rest of the cast is. The movie is atmospheric, exciting, suspenseful — the adjectives could keep on coming. Above all, it's a gripping moral drama, where multiple characters are torn between good and evil and have to define themselves by their choices.

Yet for all its virtues, The Dark Knight is very, well, dark. So much that it gets me wondering about how dark is too dark for our own spiritual welfare. I'm not sure I know the answer, but I'm sure I at least ought to spend some time thinking about it.

The biggest source of darkness is the Joker himself. Far from being funny, he's genuinely scary: He's a twisted, sadistic force of pure, chaotic evil, who torments and slaughters people just because that's what he does. The scariest thing about him isn't what he'll do, awful though that is, but what he is. He's not in it for standard reasons like money, anger or revenge, but simply because he likes destruction for its own sake.

And not just destruction, but even more than that, corruption. The Joker's ultimate goal is to make everyone else just as bad as he is — or, as he would have it, to prove that they already are that bad, deep down. It's the ultimate in egomania: the monster who just naturally believes everyone else is a monster too. In his mind, they just need him to rip away the veneer of civilization to prove it.

Making things scarier, much of the time he succeeds at corruption. Other times he fails, but he comes very close: Nearly everyone is sorely tempted to sink to his level, so much so that it's inescapably clear that evil dwells in even the best of them and, inescapably, us.

(Note: To explore this film's philosophical and spiritual underpinnings, the following sections contain plot spoilers.)

Thus, the Joker turns crusading D.A. Harvey Dent — who's every bit as heroic as Batman for most of the film — into the physically maimed, internally twisted villain Two-Face. The Joker goads a policeman into attempting to torture a prisoner (the Joker himself). The Joker turns the citizens of Gotham into frightened mobs and brings many of them to the edge of committing mass murder in order to save themselves.

And then there's Batman himself, who crosses ever more ethical lines in his drive to stop the Joker. He won't kill, but he'll do almost anything else to achieve his goals. He throws a mobster off a ledge, purposely breaking his legs. He uses his high-tech gadgets to spy on the whole city. And in a key scene, he interrogates the Joker with a vicious beating — which just eggs the villain on to gloat to the hero about how much alike the two of them really are.

There's a lot of wishful thinking on the Joker's part, but his taunts contain some truth too. Batman's not the same as him, and not everybody else is either. Batman stops short of crossing some lines (he won't kill), and even backs away from some lines he's crossed already (he dismantles his spy devices). Some civilians, too, refuse to cross over to the dark side. But for all too many, it's a close call: They're genuinely tempted, and many of them don't turn away.

On one level, The Dark Knight is an engaging morality tale. It's all about the war between good and evil, and for at least some characters, good is still standing at the end. The trouble is, we have to go through so much evil to get there that the evil still looms larger.

Violence, death (including two major characters), gruesome disfigurement, terror, madness, macabre menace — these are the things I remember most strongly, much more than the heroics of Batman and others. Maybe that's partly because Heath Ledger's Joker portrayal was so overwhelming. Whatever, the reasons, while I left the theater thinking "great movie," I also left feeling relieved it was over. I didn't feel uplifted by the triumph of good over evil. I felt more like I'd had a close call with evil myself, and barely gotten away.

I'm not the only one to feel this way. As Time magazine critic Richard Corliss put it, The Dark Knight is "bound to haunt you long after you've told yourself, 'Ahh, it's only a comic book movie.'" That's what happens with depictions of raw evil. Even when it's clearly shown as evil, at some point the benefits of wrestling with its reality may not be worth the cost to our spirits.

If some of this sounds familiar, it might be because I've written about these things before. A couple of years ago, I did a column about crime shows, which also depict a lot of evil in the course of having their heroes fight it. I won't recap all that here, except to say that now, as then, I'm reminded of the Apostle Paul's words: "Whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is anything worthy of praise, think about these things." (Phil. 4:8)

As I wrote then,

It's clear that Paul doesn't mean we shouldn't notice evil in the world, much less in ourselves: His own scriptural writings are ample evidence of that. But he's telling us where our emphasis should be. When we combat evil, it should be because we're concentrating on affirming what's good. And to do that, we need to direct the lion's share of our attention to what's good.

How much can a story wrestle with evil within us while still focusing on the good? There's no formulaic answer: Every story is different and they can't all be made to fit one mold.

But when I think of stories that make this work, I think first of The Lord of the Rings. I found this story scary when I first read it (I was 15 or so), not because the heroes fought evil creatures, but because the heroes had to struggle with evil within themselves. Frodo, Bilbo, Boromir and others — all of them found the Ring of Power corrupting their own souls. Even Gollum has just enough humanity and decency left in him, for a while, to be truly frightening: He's evil, but he wasn't always, and we can recognize just enough of his likeness to ourselves to feel a chill.

Still, my strongest memories at the end of The Lord of the Rings (in book or movie form) aren't of the evil it depicts. They're of the good things and good people. Little hobbits braving big dangers, not without fear but in spite of it. Bold warriors riding into battle against hopeless odds. Friends risking all for friends. Painful partings but joyous reunions. The simple beauty of country life in the Shire, and the strength of the bloodied-but-unbowed city of Rohan. The story glimpses into the darkness, but its heroes are creatures of the light, and the light is what dominates.

Yes, there's room for more than one kind of story. Even among good stories, though, some do us more good than others. I'll probably see The Dark Knight again in a year or two. I'll put Lord of the Rings on over and over again. We can glimpse into the darkness from time to time, but we look too long at our peril. We need to spend most of our time looking into, and living, in the light.