Madeleine L'Engle received 26 rejection letters before she could get A Wrinkle in Time published. In 1962, Farrar, Straus & Giroux published the difficult-to-categorize book, which blends science, religion and fantasy to tell the story of Meg Murray and her quest through time and space to find her missing scientist father.

But that was just the beginning of the struggle that L'Engle and her book faced, as A Wrinkle In Time has been banned or "challenged" in certain American schools, churches and libraries every decade since it was first published. In fact, the American Library Association listed it at No. 23 of the 100 most-challenged books of 1990-99, and again for 2000-09, where it came in at No. 90.

The bans, however, haven't affected sales, and in 56 years, A Wrinkle in Time has never been out of print. As of its 50th anniversary in 2012, it has sold more than 10 million copies worldwide and become a staple on school curricula. Disney has even adapted the story twice: one, a made-for-TV movie released, co-produced by a Canadian company in 2003; the other, a big budget Hollywood film starring Oprah Winfrey and Reese Witherspoon, directed by Ava DuVernay and out today.

Witchcraft, crystal balls and demons

But why has A Wrinkle in Time, a beloved children's classic for so many, faced so much criticism? The challenges vary. Some argue that it's simply too complicated for children while the major criticism has come from religious groups who question the book's mixture of science and religion. Like The Chronicles of Narnia and The Lion, the Witch and the Wardrobe, the story is deeply rooted in Christian beliefs. L'Engle, a Christian and ecumenist, was the librarian and writer-in-residence at the Cathedral Church of St. John the Divine in New York, and her book is permeated with biblical quotations and allusions. It also heavily features quantum physics, magic and philosophy — points of contention in many of the challenges, which have claimed that the book promotes witchcraft, crystal balls, demons and New Age thinking (New Age still being in its nascent years when the book was published). Jerry Falwell Ministries have been among the many to claim that it undermines faith and religious beliefs.

Finally I said, 'Ah, the hell with it.' It's great publicity, really.'' - Madeleine L'Engle

Although L'Engle has taken the criticism in stride, telling the New York Times in 2001, "It seems people are willing to damn the book without reading it. Nonsense about witchcraft and fantasy. First I felt horror, then anger, and finally I said, 'Ah, the hell with it.' It's great publicity, really.''

One particularly controversial passage places Jesus alongside the likes of Gandhi, the Buddha, da Vinci, Shakespeare and Einstein, to name a few, in a fight against darkness. Critics feared it reduced Christ's divinity, causing L'Engle to address it in her 1980 book Walking on Water, in which she writes, "to be truly Christian means to see Christ everywhere, to know him as all in all. I don't mean to water down my Christianity into a vague kind of universalism, with Buddha and Mohammed all being more or less equal to Jesus — not at all! But neither do I want to tell God (or my friends) where he can and cannot be seen!"

It's a kind of spiritual pluralism that some have found disagreeable, which has placed A Wrinkle in Time in an odd position: on one hand, it's been called anti-Christian, while on the other, with it's reliance on religious themes, it's been deemed too Christian, pegging L'Engle as a Christian writer. A claim she devoutly refutes.

"No. I am a writer. That's it," she said in a 2000 PBS interview. "No adjectives. The first thing is writing. Christian is secondary."

Filming the 'unfilmable'

It's no wonder it's taken this long to bring the story the big screen. At one point it was called "unfilmable," a dubious honour it shares with Dune (the 1984 film version was panned) and Don Quixote (which has been 19 years in the works). The rights to Wrinkle in Time were purchased in 1979 by Norman Lear, but it wouldn't reach the screen until a widely panned 2003 adaptation that, in order to avoid controversy, stripped the story of its Christian themes. "I expected it to be bad and it is," L'Engle replied when asked if the film met her expectations.

While critics of the book have accused A Wrinkle in Time of denigrating Christian beliefs, removing those beliefs in order to avoid controversy, ironically enough, only serves to denigrate the story itself.

But that hasn't stopped writer Jennifer Lee (Frozen), who was tasked by Disney to write the current adaptation and has veered down that same road of removing the overt Christian references in favour of a less controversial notion of a universal spirituality.

"One of the reasons [the book] had that strong Christian element to it wasn't just because [L'Engle] was Christian, but because she was frustrated with things that needed to be said to her in the world and she wasn't finding a way to say it and she wanted to stay true to her faith," Lee said in an interview. "I think there are a lot of elements of what she wrote that we have progressed as a society and we can move onto the other elements. In a sad way, some of the other elements are more important right now and bigger — sort of this fight of light against darkness."

Reviews for the new Wrinkle in Time film have been mixed, and it currently sits at 43 per cent on Rotten Tomatoes, lending credence to the idea that some stories are so complicated — and controversial — that there is a reason they're deemed unfilmable.

Susan Shilliday, who wrote the script for the 2003 adaptation, says it best. "It's a beloved book," she told the Hollywood Reporter. "And maybe beloved books should never be adapted."