Eh, it’s a twist that panders to yesterday’s culture warriors. People who enjoy having their own worldview affirmed and then making others “deal with” that worldview.
Would you have wanted the ending to be the pope to be elected and everyone hugging and waving goodbye as the camera ascends to the heavens, where God then turns and winks at the audience? Or do you want something to talk about that has an effective tie to the theme of the film.
Watch a documentary if you want an accurate description of the papal voting process.