Since its publication in 1962, A Wrinkle in Time has become one of the mostfrequently banned or challenged books, for multiple reasons. People have argued that it’s too complicated for children, and earlier critics disapproved of its plucky female protagonist. Among conservative Christians, one of the biggest objections has historically been the way that the book’s author, Madeleine L’Engle, mixes science and religion.

A Wrinkle in Time tells the story of Meg Murry, a girl who travels through time and space to save her father from evil forces. L’Engle, an Episcopalian, imbued her novel with religious elements and ideas. Yet at the time, many Christians viewed them as unorthodox.

“She was engaged in this project of revisioning Christianity, pretty much like C.S. Lewis was with The Chronicles of Narnia,” says Marek Oziewicz, a professor of literacy education at the University of Minnesota. It was “a vision of Christianity as a form of science, and science as a form of search for spirituality.”

The idea that science and religion can coexist may seem less controversial today, in an era where the Pope has publicly stated that scientific concepts like evolution and climate change are not at odds with Christianity. But in the decades following the book’s release, many U.S. Christians believed there was a conflict between contemporary scientific findings and the Bible’s vision of the world, particularly as astronomers and physicists learned more about the cosmos.

L’Engle felt differently. “She believed that there’s overlap between science and spirituality, and that new Christianity would be fully compatible with what modern science tells us about the universe,” Oziewicz says. To her, newly discovered parts of the universe didn’t represent a challenge to the Bible. Rather, she viewed them as part of God’s creation.

A Wrinkle in Time also sparked religious controversies because of the type of characters it included. Three of the main characters—Mrs. Whatsit, Mrs. Who, and Mrs. Which—are at once spiritual, angelic andkind ofwitchy. This led some to claim that the book encouraged witchcraft, or heretically conflated Christianity with the occult. One scene in particular—which depicts Jesus, Gandhi, Einstein, and the Buddha standing together against the forces of evil—offended Christians who thought L’Engle was equating these four figures.

“I’m not sure if she was trying to equate them, but she was definitely speaking about something that she called the ‘heresy of love,’” Oziewicz says. The heresy of love was L’Engle’s belief that Christians incorrectly placed exclusions on God’s love. By including these three figures next to Jesus, he says, “she was saying, pretty much, ‘Who are you to tell God whom he or she wants to include or exclude?’”

Producers have been interested in adapting A Wrinkle in Time since at least 1979, when television creator Norman Lear bought the rights to the book. But the story wouldn’t reach a film or TV screen until the 21st century; first with a made-for-TV movie in 2004, and soon with director Ava DuVernay’s 2018 feature film, which premieres on March 9.

It’s not clear why it took so long to adapt the book into a film. A Wrinkle in Time’s conceptual plot has long been considered unfilmable, so the technical issues of how to adapt it likely played a role. Additionally, the hold-up may have been due to the various controversies the book has stirred up, particularly among conservative Christians.

Perhaps for this reason, Disney’s 2004 TV version of A Wrinkle in Timeleft out a lot of the book’s explicitly religious elements. In any case, it didn’t get good reviews, least of all from L’Engle herself. When Newsweek asked her if it met her expectations, she replied: “Oh, yes. I expected it to be bad, and it is.”

DuVernay’s film, also a Disney movie, seems to have followed a similar path by excluding some of the religious elements. But today, this editorial choice may cause a different kind of controversy. A few days before the film’s premiere, the conservative news site The Federalist published an op-ed by a Christian writer saying she hoped the film didn’t remove these aspects of the novel.

Rather than arguing that these parts were heretical, the op-ed extolled the book’s Christian principles. To be sure, there are still conservative believers who don’t feel that way. Yet more than 50 years after its publication, there seem to be moreChristianswho appreciate A Wrinkle in Time for the very religious elements that once made it so controversial.