“The Great Divorce,” based on C.S. Lewis’ classic theological fantasy about heaven and hell. Produced by the Fellowship For Performing Arts; showing at the Pearl Theatre, 555 West 42nd St., New York.

Most of the action in “The Great Divorce” takes place on grass. The three actors, all barefoot, walk and tiptoe and run on the lush greenery as they bring to life one of C.S. Lewis’ most imaginative stories.

Max McLean, the founding director of Fellowship of the Performing Arts and one of the story’s adapters, said the decision for bare feet was made early on in the creative process: “The grass motif was a very central metaphor to capture.”

That metaphor is essential to the intriguing plot: Travelers from a gray place (Hell?) are invited by saints to take a cosmic bus trip through Purgatory to the far mountains, the land of joy: Heaven. Along the way, they realize they are not substantial enough to deserve the reward; they are such lightweight beings that even the tips of blades of grass hurt their feet because they can’t step on it hard enough to bend it over.

The story, then, is about the journey Lewis is invited on, from ghost to solid man. This is the journey, he supposes, of Purgatory, which is meant to toughen up humans so they can endure the weight of God’s glory. Lewis is the narrator, with the production’s three actors assuming multiple roles representing many different characters.

As McLean notes, Lewis’ tale was a challenge to present on stage. It’s incredibly dense, both artistically and theologically. To do it justice, McLean knew special effects would have to be involved. “The most efficient way to set the story was to use a video screen to show really distinct images, to show the tremendous move from the banality of the gray town to the lush beauty of the outskirts of Heaven.”

The other way to tell big stories on a limited budget, says McLean, is to be inventive. Fellowship for Performing Arts, the New York company McLean founded in 1992 to produce theatre from a Christian worldview, may not have all the same resources as other theaters in the area, but it does have access to the important ones: the creative people who put on shows.

“One thing New York has is great actors,” says McLean. So he found three of them, who together give life to more than a dozen characters throughout the 90-minute play. The demands of the script are stringent, and each meets the challenge head on.

Joel Rainwater plays Lewis’ character — his is the perspective the audience naturally follows. The other two actors, Christa Scott-Reed and Michael Frederic, play Lewis’ fellow travelers and the Bright Spirits who come to aid them in their transition to Heaven — should they choose to do so. Remarkably, most of them don’t.

In addition to playing other spirits, Frederic most memorably plays George MacDonald, the 19th-century Scottish author whom Lewis calls his Master. Lewis attributed the “conversion” and “baptism” of his imagination to MacDonald’s “Phantastes”.

“I saw the bright shadow coming out of the book into the real world and resting there,” he writes in “Surprised by Joy,” “transforming all common things and yet itself unchanged. Or, more accurately, I saw the common things drawn into the bright shadow.”

Just as Virgil was Dante’s guide in “The Divine Comedy,” MacDonald was Lewis’ through his cosmic bus ride. MacDonald not only explains to Lewis what he’s seeing in Purgatory, but delves into some of the theological significance of the bus trip. For that reason, MacDonald is of great aid both to Lewis’ reader and the play’s audience. At one point in the play, to illustrate a truth about Hell, MacDonald shows Lewis a tiny light shining through a crack in the grass. All of Hell fits into that crack, he says. That’s what makes Hell so difficult to understand, he says: It’s so nearly nothing. Lewis’ bus trip through that crack didn’t consist so much in going as it did in growing: ”The voyage was not mere locomotion. That bus, and all you inside it, were increasing in size.”

Heaven, on the other hand, he tells Lewis, is big, magnanimous reality itself.

After his conversion to Christianity in 1929, Lewis remained a lifelong Anglican. But many have argued his theology is closely aligned with Catholicism. Perhaps the reason Lewis never traveled to Rome is because it would have meant leaving Belfast — a departure any good Englishman would have found difficult to make.

Notably, the purgatory that Lewis explores is not the one of Catholic tradition — the Reformers had good reason to throw doubt on that Romish doctrine, he wrote — but the one John Henry Newman explores in “The Dream of Gerontius.” In Newman’s vision, says Lewis, “the saved soul, at the very foot of the throne, begs to be taken away and cleansed.”

Lewis continues:

Our souls demand Purgatory, don’t they? Would it not break the heart if God said to us, ‘It is true, my son, that your breath smells and your rags drip with mud and slime, but we are charitable here and no one will upbraid you with these things, nor draw away from you. Enter into the joy’? Should we not reply, ‘With submission, sir, and if there is no objection, I’d rather be cleaned first.’

Lewis compares this cleansing phase to gargling with water at a dentist’s office after a tooth has been pulled.

Characters can leave behind the Gray Town if they agree to being cleansed. It’s not that Heaven doesn’t want them if they are dirty; rather, in their present state, they can’t even bear the weight of raindrops. How, then, can they bear the weight of the fullness of joy?

Although the play consists of a great deal of theological surmising, McLean, like Lewis in his own introduction, reminds audiences the work is primarily fantasy. That is, he says, the story tries to have a moral, but it doesn’t try to guess about the reality that awaits us on the other side of death.

The best way to view “The Great Divorce,” writes Lewis in his introduction, is as an “imaginative supposal,” which is how Lewis describes “The Chronicles of Narnia,” despite a litany of voices insisting on its allegorical status. Suppose we could see our lives from the other side of time, the supposal goes. What would we learn?

According to Lewis’ story, says McLean, we’d learn “that our choices matter, and they matter every moment, and our eternal destiny is determined by choices we make here and now.”

In that sense, the story suggests that Heaven and Hell are, as the Orthodox hold, choices.

“One of the great takeaways of ‘The Great Divorce,’” says McLean, “is that the people in the Gray Town want to be there. If given the choice of heaven or the Gray Town — they prefer the Gray Town.” As Lewis quips elsewhere, the reason the pure in heart are blessed with seeing God is because only the pure in heart would ever really want to.

Lewis argues this point in “The Problem of Pain,” claiming, “The door of hell is locked from the inside.” Some people want hell; they get their wish. But all those who truly desire joy, MacDonald tells Lewis, find it. “There are only two kinds of people in the end,” MacDonald tells Lewis. “Those who say to God, ‘Thy will be done,’ and those to whom God says, ‘Thy will be done’.”

The latter group, when offered the expansive joy and laughter and beauty of the universe, close in on themselves and choose their own ego. They believe, as Milton said, that it’s better to reign in Hell than serve in Heaven. They are, as Lewis suggests in “The Problem of Pain”, like Shakespeare’s evil Richard III, who utters, “Richard loves Richard; that is, I am I.”

In the end, as MacDonald points out to Lewis, those who shut themselves up in hell realize that they’ve been there all their lives. So, too, do those confirmed in the joy of Heaven realize they’ve lived their entire lives in the bliss of God.

Of course, there are incredible theological ramifications for these thoughts — but Lewis isn’t a theologian. In fact, it’s precisely because he wasn’t a trained theologian that he saw the immense success he did, says McLean. His education consisted of the classics and philosophy and literature, which means, says McLean, Lewis brings a much more artistic, imaginative approach to these questions than would seminary-trained thinkers.

McLean and company have certainly taken a cue from their muse in his staging of this imaginative supposal. Embracing whimsy and avoiding heavy-handed theological exposition, “The Great Divorce” — like all good plays — invites its audiences to consider their own mortality and morality, and to reflect on their decisions in this time and place with a eye wandering toward another.