Popular culture evolves quickly, but few could have foreseen how that most glamorous of monsters, the vampire, would shift from being an icon of terror to an object of romantic desire. This shift is traceable to one key source - Stephenie Meyer's teen romance, the Twilight Saga. As the final film adaptation of Meyer's tale of the dangerous lovers Bella and Edward hits our screens today, I believe that it leaves the Church with intriguing and perhaps troubling theological challenges.

If her series has not sunk its teeth into the UK in quite the same way as it has into American throats, there is no doubt that it is an extraordinary phenomenon. It is responsible not only for a new genre, the "dark romance", but even for the Fifty Shades books ( Comment, 14 September), which were originally Twilight fan-fiction. More than 100 million copies of the four novels have been sold worldwide, mainly to women and girls. If the Church hopes to comprehend and respond to the emer-gent world-views of young women, it needs to engage with Twilight and its imitators.

At one level, the Twilight Saga has rightly been compared to Harry Potter. Both share a narrative magic that makes people - young and old - want to climb in and live in the story. In so far as we are the kind of creatures who seek stories to live by, fantasy tales invite people to lose themselves in the narrative, but also to explore their identities.

The protagonist of Twilight, Bella Swan, is presented as an utterly ordinary girl, lacking particular talent or beauty, and, as such, acting as an "every girl" figure. Her character invites teenage girls (and those of us who should know better) to identify with her, trying on feelings, roles, and ideas in a safe environment.

The Twilight Saga, focusing on the complex love story between Bella and a vampire for ever frozen at 17, offers characters who are broad enough for people to identify strongly with them, and discover themselves in the pages. They can live out their romantic fantasies of finding the perfect partner and relationship. This is a magical world, populated by mythic creatures who exist just below the surface of the everyday, all wrapped up in romance, sacrifice, and temptation.

The distinctiveness of Twilight lies in the way it takes fantasy and mythic elements, and combines them with romance and a veneer of danger. Meyer draws not only on conventions familiar to readers of old-fashioned Mills & Boon romances - the strong brooding male figure, the young vulnerable woman, and so on - but the edgy tropes of "proper" fiction, especially Wuthering Heights. The constant refrain of Bella and Edward's romance is how dangerous it is: Edward has the power to kill Bella in an instant, and yet Bella exercises such a hold over him that he could destroy himself at her command.

While religion is barely mentioned in the saga, Meyer is a committed Mormon, and faith is the barely disguised subtext of the story. Much has rightly been made of Twilight's extraordinarily old-fashioned - indeed, reactionary and oppressive - image of relationships. As Robert Pattinson, the English actor who plays Edward in the film versions, has suggested, Twilight makes abstinence "sexy" for teenage girls.

The sub-text of the books is that sex between Bella and the powerful vampire Edward might actually kill her. Indeed, it is only after they are married that Bella and Edward take the "risk" of "doing" it.

If that is old-fashioned, critics have rightly pointed out how Meyer turns Bella into an almost anti-feminist hero, interested only in pleasing "her man", and locating her goals and dreams entirely around making him happy. No sensible apologist - and certainly not a feminist like me - can justify the way in which Bella buys into a romantic dream that so utterly denigrates her own identity.

There are, however, dimensions of Twilight which represent a genuine opportunity for exploring faith in surprising ways. If the series is essentially an advert for sexual abstinence, it is - more interestingly - rich in suggestive religious themes. Fundamentally, Meyer explores the shape and nature of temptation, and the place of sacrifice within it.

The cover image of the first book in the series shows a woman's hands holding a shiny apple, a deliberate reference to the Adam and Eve story. While much of the narrative centres on whether Edward - as a "good" vampire - can resist the constant temptation to drink Bella's blood, he also represents forbidden fruit for her. Again and again, Edward is presented as unhealthy and bad for her, pulling her away from the natural course of her life. And yet, as each negotiates temptation and makes sacrifices for the other, both are changed.

In a conscious echo of Isaiah 11, Meyer presents Edward as a lion who falls in love with Bella, the lamb. Here, then, is a popular-culture image that opens up to an unchurched generation what it might mean for people - natural enemies - to be converted to one another. Twilight offers suggestive images of our call to reconciliation and peace.

If this is open to the claim that it does not go deep enough - Meyer's interest in transformation is al- most exclusively individualistic and grounded in romantic love - the very fact that these images are there is striking.

One of the boldest moves is to suggest that not only sacrificial love (agape) but erotic love (eros) is redemptive. Twilight presents a model of a familiar picture of agape in the endless opportunities that Bella and Edward have to sacrifice themselves for the sake of the other. More interesting, though, is the suggestion that the nature and intensity of their desire is transformative. One reason why Twilight has been a worldwide hit is that it is a story about true love's conquering, despite the odds. And at the heart of that is eros.

Christians, for any number of reasons, have often been troubled by desire and erotic love, seeing it as selfish. Yet Twilight reminds us of its power to change us. Eros - as many spiritual writers have reminded us - is at its most profound about the desire to give oneself to one's beloved, in service, support, and blessing. It is the yearning towards union with the other, in such a way that it sets the other free.

It is the love modelled in the unity and freedom of the Trinity. At the heart of Christ's coming into the world is eros - desire. God's sacrificial love is grounded in his desire for us, and we are invited to make an appropriately powerful response.

It would be absurd to spare Meyer's series extensive criticism. If her portrayal of Bella as a representative young woman is, at best, troubling, and, at worst, likely to encourage girls to indulge in horrific patriarchal fantasies, there are many other troubling aspects. Her portrayal of Edward's family of good vampires verges on a celebration of the worst excesses of consumerism and capitalism.

The sub-text of the novel - that the only good relationship is a married one with a man at the head of the family - is laughable. None the less, her ability to take well- established tropes of romance and infuse them with religious themes is unusual.

Indeed, if Twilight is hardly wonderful literature - not achieving the sheer delight of Harry Potter, or the completeness of the likes of Tolkien - it remains interesting precisely as an icon of our human desire for magic and enchantment. It has perhaps become a cliché to talk about how our culture has become "disenchanted"; that is, about the extent to which the traditional "magic" of the Church - its sacraments and stories - has lost its grip on people's imaginations.

One symptom of this disenchantment is the extent to which people throw themselves into the picaresque and somewhat febrile imaginings of a Stephenie Meyer. While it is easy to say, "Oh, what a feeble narrative to give yourself to," that is to miss the point. Unlike the Christian story, a fantasy such as Meyer's makes no specific demands or expectations on a life. You can lose yourself within it, and enjoy it as sheer "play". Part of the reason that many struggle with the Christian story is that it is not merely about escapist fun: it is about becoming our true selves.

None the less, the success of work such as Twilight challenges the Church both to rediscover the enchantment within the greatest story ever told, and also to find ways to help people discover themselves in it.

It is easy to reduce the Christian story to a set of moral imperatives or childish stories. Actually, Jesus's story is far from being childish: it is mythic in the proper sense. Jesus's story is foundational for our true identity; it provides a proper basis for living an authentic life.

While Christianity should never lose sight of the ethical, aesthetic, and social implications of its foundational story, the Church faces a continuing narrative challenge: not only to find ways to bring the story alive for communities and individuals, but to help them experience it as a place where, as they lose themselves within it, they begin to discover their true selves.

The Revd Rachel Mann is Priest-in-Charge of St Nicholas's, Burnage, Manchester, and poet-in-residence at Manchester Cathedral. Her book Dazzling Darkness is published by Wild Goose this month.