Not OP here, R37. But I can go one step further. I bought the tape. I thought it was great (as a kid) but I had also coming out at 15 to my parents and by then, at 18, was already quite hurt by the Church, having also been smart enough to know when a priest was coming on to me and I got away from him. My cousin did not. I loved the music, the serenity, the peacefulness and sensory experience of the mass but the abuse, sexism, and homophobia - no. So when I left the Church I felt I had lost something I've never experienced in any other church – the mystery of the Church that Catholics find lacking elsewhere. I have no idea of Pielmeier had a beef with the Church but as I grew older it seemed to me he was more going after ex-Catholics and this is what failed the story.
I loved Anne Bancroft in it. She was a dead ringer for one of the nuns that taught me as a child and the way she seemed alternately judgmental and compassionate, right up to the final interrogation of Agnes. She seemed genuine to me. Tilly was very good in portraying someone you could believe was "touched" in all the meanings of that word. Fonda though seemed flat, to me, I never bought it when she said she loved Agnes. And the play never explained that leap. The whole "my sister died in a convent" is so contrived and the crazy mother Anne Pitoniak (a great actor) was just so expected. If Fonda had that same sense of loving the Church despite all of that and there was more about her grieving over her sister, it might have been believable, but that whole bit is insane.
In retrospect, there were ways around it -- Livingston (Fonda) herself should have been more torn as a Catholic, still praying, wanting to take communion, etc., wanting to believe. If she doesn't believe it's a virgin birth, she must think Agnes is not mentally well so she could've killed the child (which she actually did). If the film had played off of her doubts, it would've made more sense - maybe not willing to admit she believes Agnes in some weird way but that there might have been a birth that the Church would want to cover up for some reason.
They also have the older nun in the film tell Agnes to go to the barn on her deathbed (don't remember if this is in the play) but she died. If there had been some other way to show that she told Agnes things that seemed mystical (maybe a nickname her sister had used for Livingston and the old nun told her she would come). Doesn't Agnes do something like close to that in the film? It would've been better coming from the nun who had the vision of the man in the barn. You could at least have made it believable that this nun had a way of giving the impression that she had some special insight, or that LIVINGSTON started to believe that maybe it was real. The play was a three-hander - the film clearly wasn't. But they could have kept the old nun alive and said something to Livingston to just plant a seed - a doubt - in Livingston's mind that the nun might have had a vision or was just senile and Agnes bought it.
Nor was there any way they could get around the imagination, since it was a film there was a need to show the impregnation - so we get doves and light. So believers and nonbelievers alike are supposed to think what? It really MIGHT be God? OOOOH! Why not something that looked like an angelic man? Agnes says she saw one at the end of the filn, so why not show it. Catholicism accepts that God came down from Earth and "became man", but to have there be actual sex would have been so contrary to the Christian fantasy and so not-Catholic (REAL sex is for marriage only!)
The problem with the film, more than the play, is that you never got a sense of the mysticism of the Church so the whole idea that Agnes believes it makes sense. The score is beautiful but the sublimated sensuality of the Church is missing, especially since it's old school Catholic (stern and cold) – a subtle homily, the touching, the holding hands, the truly communal singing, even Communion is used for a plot twist. It just feels like a cold film.