Generally speaking, additions are more welcome than changes, as long as the additions do not alter the canon story in any way
. Ie, most people did not object to the scene where Boromir teaches Merry and Pippin the basics of swordfighting*, even though that was certainly not in the story, because it was seen as something that could have happened and just been left out. Whereas the scene where Boromir held the Ring in his hand (when it fell off Frodo's neck in the snow) got more complaints of the 'but Boromir never touched the Ring!' variety. And that's not even getting into changes that directly contradict the story, such as Aragorn beheading the Mouth of Sauron, or Haldir's death at Helm's Deep.
*The only objections I've heard to that scene are of the practical variety, as you maybe shouldn't do that lesson with live steel and beginners, or that it doesn't address the clear height/strength differences between hobbits and humans realistically, etc. No one argues that it was out of character for Boromir to teach them, or for Merry and Pippin to want to learn, or for such a thing to have happened in the 'down time' of the journey. It was therefore generally viewed as an acceptable 'missing scene' addition to the story, with complaints limited to how it was portrayed, not that it was portrayed at all.
Given that, there would be *strong* objections to making one of Tolkien's closest friends into an antagonist just for the sake of conflict in the storyline, but there would maybe be less objection to having one of his (say) unknown rugby teammates have the type of antagonistic relationship that the TCBS would be in such contrast to. No one knows much about those boys, so there's room for invention without contradicting what we do know, and there would be no need to make such a character a caricature - one could do enough research to make him a believable representation of someone of that time and place. But I wasn't joking when I said I don't know much about this part of his life. If the majority of his schoolmates were Catholic, there's less opportunity to introduce the proto-CS Lewis type of friendship there. My own experience with attending a Catholic high school in America in the '90s was that about half the students were from Catholic families and half from Protestant, and that many were 'raised Christian' but certainly not practicing/believing Christians. I recognize that this has little to do with the experience of attending a boys boarding school in England pre-WWI, though.
But again, this begs the question of what story you set out to tell. If the question is 'how could one showcase Tolkien's faith in a biographical film?' there are methods that can be suggested. That doesn't mean that this particular film project should have done these things, but it doesn't really surprise me to hear that they toned down his faith. It's difficult to convey and probably less comfortable to the filmmakers to try.
'Lives of the Saints' videos are an entire genre. Naturally, they focus on the faith of the people portrayed. The production quality is typically less good than your average feature film for a general audience, but that doesn't mean they're all terrible or badly written/acted. It's more that they're in the tradition of hagiography, which celebrates faith/holiness in a way that other stories do not. Some...are better than others. I've never seen a decent film representing the life of St. Francis of Assisi. Very few people 'get' him, even the ones who like him! He's quite incredible, but to a modern audience he's more a hippie who liked animals - which isn't wrong, but seriously misses the point. His story is difficult to capture. St. Thérèse of Lisieux is even more difficult...her story is entirely interior, so much so that her close family members and those she lived with in the convent (some of whom were the same people!) wouldn't have known it if she didn't write an autobiography. There's a few key events to tell, of course - the death of her mother, her vacation to Rome where she had a chance to have an audience with the pope, and asked him for permission to enter Carmel at the age of 15. But for the most part...everything that she was thinking and feeling and doing was...interior. And her confessor was convinced that she'd never in her life committed a mortal sin, so, there's that, too. She's going to come across as unreal if you tell her story at all faithfully.
Some saints are easier to make a movie about. There have been multiple films about Mother Teresa - she was well known and people were curious about her, so that seemed a natural topic, and what she did was fairly unique in a lot of ways. In general, the backdrop being dramatic helps. So, to list some examples:
Karol: The man who became pope (2005) tells the story of Karol Wojtyla (Pope John Paul II). The backdrop begins with the German invasion of Poland in WWII, and then moves into Soviet-controlled Poland. The halfway point of the film shows his ordination to the priesthood corresponding with the end of WWII. So, it's fairly easy to portray his faith as being in opposition to Nazis and Communists, and for his form of 'resistance' to be giving hope to people and continuing Polish culture in the face of forces that wished to demolish it. It ends with him being elected the first non-Italian pope in 500 years; having established his love for Poland over the course of the movie, it was clear that accepting meant going into exile for him. Overall, I would say this is a fairly well-done film in this genre. The production quality is high, and the story has nuance. It's not strictly about piety. Still, if you want to know about his life, I would recommend reading George Weigel's
Witness to Hope biography instead.
Molokai: The Story of Father Damien (1999) tells the story of a priest who went as missionary to the Hawaiian leper colony. It of course touches on themes of people being outcast and needing an advocate, fears of incurable diseases, and what happens when you have lawlessness on an island. Also, you might recognize the actor who plays Fr. Damien, as he was later Faramir in Peter Jackson's
Lord of the Rings. He comes across as a bit of a relentless simpleton here, though clever in his own way. He is fighting against despair and injustice and against the plight of his people being ignored, and he is doing it by accepting them, serving them, and holding very strongly to who he is. The challenge is to portray someone who loves selflessly and is very willing to take risks.
The Song of Bernadette (1943) tells the story of Bernadette Soubirous, the visionary at Lourdes. You can tell that this film was made for an audience that would be quite accepting of faith in general; but it is still a bit more 'general audience' than the other two I've listed. Here, there is a bit of the spectacle of the miraculous, with the story focusing on her vision and the healing miracles there.
A more 'typical' film in this genre might be the life of Padre Pio in Italian, Padre Pio: Miracle Man (2000) (
final clip). I would say that this film would be very difficult to understand outside the context of Padre Pio's faith. His faith and his life are...pretty much the same thing. The story is mostly about miracles and conversions. (In this clip, he performs an exorcism after having been beat up by the devil the night before:
clip; and in this one, he yells at one of his supporters and publicly shames him because he dared insult a bishop:
clip) What he's fighting against are quite literally the devil and sin, so.....
Should someone try to tell Tolkien's story within this genre? I'm not sure it's a great idea. There's not really any need to portray the man as a saint. But I do think that a story of his life that leaves out his faith is leaving out something that was very important to him. So, finding ways to integrate his faith and portray it are worthwhile, even if that's not the central point being made.