C. S. Lewis was not a man to equate modernity with progress. In ''The Allegory of Love'' (1936), his first work of criticism, he made the case for Edmund Spenser's ''Faerie Queene,'' the 16th-century chivalrous epic, dismissed in Lewis's day as outdated. It was Spenser, he said, not the later Romantics, who shaped our view of marriage as a bond of love -- a notion, he added dyspeptically, that seemed on the verge of being forgotten: ''Feminism in politics . . . and, above all, the discoveries of the psychoanalysts, have undermined that monogamic idealism about sex which served us for three centuries.''

Besides being a scholar of medieval and Renaissance literature, Lewis was a combative Oxford don, a devout Christian and, of course, the author of the children's series ''The Chronicles of Narnia.'' He would have made short work of his current American publisher, HarperCollins, and his estate (he died in 1963), if he'd been around to read a memorandum leaked to the press earlier this summer in which they revealed their desire to distance the Narnia chronicles from ''Christian imagery/theology,'' presumably for fear of scaring off non-Christian parents. The memo made obvious what Lewis fans suspected, which is that the people charged with protecting his legacy aren't doing their job. They have also announced plans to publish Narnia sequels, as if Lewis were as replaceable as the writer of a Nancy Drew.

Children's literature is big business, and you can see why HarperCollins would want to exploit a brand as well known as Narnia. But if Christianity is an obstacle, then the publisher has a problem. Reread the novels as an adult and you'll see that they are Christian through and through. It's not as if Lewis composed some children's stories, then sprinkled on a dusting of religious imagery that a sequel writer can easily sponge off. At every level except the most superficial, they're an explicit allegory of faith.

Lewis began his story of English schoolchildren, talking beasts, Arthurian princes and limpid northern landscapes as a straightforward fairy tale, but it quickly turned into a testament to his love of God. Halfway through the first book, he dreamed about a lion. ''I don't know where the Lion came from or why He came,'' Lewis wrote. ''But once He was there He pulled the whole story together.'' The lion was Aslan, the Christlike redeemer of Narnia. After that, Lewis realized he could use his tales to reanimate the Hebrew Bible and the Christian Gospels, rich sources of stories impoverished by being made obligatory: ''Supposing that by casting all these things into an imaginary world, stripping them of their stained-glass and Sunday school associations, one could make them for the first time appear in their real potency?''

That's precisely what he did, which is why so many of us love the Narnia stories so fiercely, whether we're Christian or not. The intensity of Lewis's religious feelings has been translated into an overpowering longing for goodness, as well as an anguished sense that it could be taken away at any moment. In ''The Magician's Nephew,'' Aslan brings the Edenic Narnia into being and teaches the animals to talk, as if he were God and Adam rolled into one. Narnia is a place of lustrous magic, sublime beauty and tragic fragility, like the medieval visions of Paradise that inspired it.

Narnia is Christian in its depiction of not only the good but also the bad. Narnia's enemies are Christ's enemies, and they're eerily horrific and thrilling because they evoke two millenniums' worth of Christian demonology. In ''The Lion, the Witch and the Wardrobe,'' Lewis reproduces the Passion of Christ, complete with nasty Jews. During the final negotiations between the Wicked Witch and Aslan, the witch concedes defeat but claims her right to Edmund, the schoolboy who betrayed Narnia by foolishly siding with her. It seems an ancient law engraved on a Table of Stone grants her the right to kill any traitor. Invoking, implicitly, Shylock's pound of flesh, she declares that Edmund's ''life is forfeit to me. His blood is my property.'' Aslan agrees that her legalistic reasoning is sound, but asks her to kill him instead. The scene in which she shaves, binds and executes Aslan just before his resurrection is a fairy-tale Oberammergau, filled with ogres, apes, dwarves, hags and incubuses who grin and kick, hit, spit on and jeer the captured lion.

Muslims also haunt Narnia -- or rather, cartoon infidels, a turbaned, dark-skinned people called Calormenes, who live to the south of Narnia. The Calormenes are a greedy, cruel, proud, enslaved and enslaving race. Their god is a murderous demon named Tash. They speak an argot filled with cloying, ingratiating phrases and live in cities that reek of dung and sweat. The Narnians, by contrast, are fair, blond, noble and free: ''They walked with a swing and let their arms and shoulders go free, and chatted and laughed. . . . You could see that they were ready to be friends with anyone who was friendly and didn't give a fig for anyone who wasn't.'' The Calormene boy who sees this and admires them turns out to be a Narnian foundling. As a Calormene warrior points out to the boy's adoptive father, ''your cheek is as dark as mine but the boy is fair and white like the accursed but beautiful barbarians who inhabit the remote North.''

A rather clerical fear of the female also pervades Narnia. Women are good when schoolgirls, mostly evil when grown. The Wicked Witch is huge, gorgeous and wild, but underneath her disguise, she's a serpent. At one point she casts a spell over a Narnian prince, making him dance attendance on her. ''Where I come from,'' says a schoolgirl shocked by this spectacle, ''they don't think much of men who are bossed about by their wives.'' There's anti-Catholicism here too, at least if you accept one scholar's thesis that the story of the ape who makes a false Aslan out of a donkey in a lion skin is an attack on papist idolatry. (Lewis was Anglican.)

In ''Surprised by Joy'' (1955), his autobiography, Lewis talks of being seized at an early age with a passion for what he calls ''Northernness.'' It awakened his literary faculties, filled him with unnameable longing and opened his eyes to nature. The works that aroused him in this way were the operas of Wagner and books of Norse mythology. So besides Christianity there's a great deal of ''Northernness'' in Narnia, and other influences too, most of all ''The Faerie Queene,'' with its pagan and Christian imagery pressed into service in a war between the starkest moral oppositions: Light versus Dark, Truth versus Appearance.

In short, when it comes to Narnia, we are not in the modern world. We're inside Lewis's bookish mind, an archaic universe of extremes -- profound evil, inexpressible sweetness and heartstopping dramas of the passage from the one to the other by means of grace. The Narnia chronicles are glorious, and they're also very dark, like the literary traditions they're steeped in. No matter how much their outmoded mores may trouble you, you can't alter them without destroying the soul of Lewis's creation. Embrace Narnia or reject it, but don't bowdlerize it.

Drawing (Robert Grossman)