For years, physicists have been searching for “the theory of everything,” an understanding of all physical aspects of the universe.

“If we do discover a complete theory, it should in time be understandable in broad principle by everyone, not just a few scientists,” theoretical physicist Stephen Hawking wrote in his 1988 best-seller, “A Brief History of Time.”  “If we find the answer to that, it would be the ultimate triumph of human reason - for then we would know the mind of God.” 

The existence of God is a debate that Hawking engages in with his wife, Jane, in the new film about the couple’s relationship, appropriately titled, “The Theory of Everything.”

“They seem to have polarized views on religion and God and whether there is a need for one or whether God exists at all,” producer and screenwriter Anthony McCarten told FoxNews.com, highlighting a major point of contention in the Hawkings’ 25-year long relationship. “Stephen’s quite mischievous on this point, and it’s quite hard to pin him down. At certain times, he sounds very atheistic, at certain times, agnostic… Jane’s position has been constant – she’s a person of faith. She defines herself as a High Anglican, and draws a great deal of sustenance from her belief in God.”

McCarten decided to write the film after reading Jane’s 2007 biography, “Traveling to Infinity: My Life with Stephen.”

“There was this one-of-a-kind story – extremely emotional and so unexpected,” McCarten says of his “lightbulb moment” when reading Jane’s book. “I thought if I could marry that story with everything I knew about Stephen Hawking, we would really have something special.”

The film follows the Hawkings’ courtship, marriage and eventual separation – and the debate of the existence of God is a constant in their relationship.

“This little friction between the two of them is something that is threaded right through the script,” McCarten explains. “But in typical Stephen Hawking mischievousness, what should be the last word on the last line of his most famous book – is the word God. And in one of the scenes of the movie, Jane interprets this as a major concession.”

Concession or not, Jane and Stephen’s marriage eventually dissolved and they both moved on to relationships with other people, something “The Theory of Everything” doesn’t dance around.

“One of the biggest challenges of this project, aside from disseminating the science, was doing justice to a love story that I didn’t think had a precedent in cinema,” McCarten told FoxNews.com. “And usually with these kind of ideas, there’s a good reason why there’s no precedent in cinema – because it’s super hard to pull off. Audience sympathies can be destroyed in a heartbeat in a story like this. So it really was a high wire act. It required that every one of the characters involved be portrayed in all their complexity. That there be no judgement on any of the characters and that everyone gets their day in court. And then the audience could come in and make their own decision, but we’re not judging them and maybe you won’t either.”

Despite the failure of the Hawkings’ marriage, “The Theory of Everything” is still a tale of a great romance – if an unorthodox one.

“There’s no way in my mind that this is anything less than a triumphant story – and that is not threatened by the fact that they moved on in their lives and found other people,” insists McCarten. “Their achievements were too great to be anything less than triumphant. It would be like saying, ‘Oh, I climbed Mt. Everest, but on the way back down I stubbed my toe – therefore, it’s not a happy ending.’ The stubbed toe doesn’t diminish the climbing of a mountain.”

Even though they have both moved on, both Jane and Stephen loved the watching the chronicle of their lives together.

“We showed them the final product – separately,” McCarten told FoxNews.com. "Jane said that she felt like she was floating on air after seeing the film, and Stephen shed tears. His nurse wiped the tears from his face after seeing the film.”

“The Theory of Everything” opens on Nov. 7.