Was this movie on the 'Condemned List'?
There was (is?) an organization called something like the "Catholic League of Decency" that used to issue rate all Hollywood movies and assign them a "sin rating."
All Disney movies received "A" ratings - which is like the old "G" rating, except that it carried with it a religious connotation: watching an "A" movie did not offend God.
"B" designated a questionable religious call, something like okay for parents but not young people.
"C" was "CONDEMNED" - and that meant if you saw a "C" movie you immediately committed a mortal sin (same as not attending church on Sunday). Two "C" movies were the early 60s' "Mondo Cane" (a documentary which showed various mating rituals in tribal communities - the nudity and pelvic thrusts got you in trouble) and Billy Wilder's "Kiss Me Stupid!" (Dean Martin has an wild affair with Kim Novack while he is married).
"The Nun's Story" seems like a good candidate for a "C" rating: it blows the lid off the wacko world of Penguin Island and shows what insane women run the convent.
I can only imagine the Catholic Church was NOT very happy about THAT - and would have actively discourage its members from seeing this movie.
"Don't call me 'honey', mac."
"Don't call me 'mac'... HONEY!"