Fridge / Martyrs

• Morton's Fork: As Renegade Cut points out in his analysis of the film, the cult is essentially doomed regardless of the results of their efforts. Assuming Anna did catch a glimpse of what lies beyond death, there are really only two options: either she sees nothing or she does. If she sees nothing, then the cult has been torturing countless innocent people for no reason. However, even if she did see something, things do not get better. Anna seeing a definitive afterlife comes with the possible confirmation of at least one religion. Regardless of which one, most religions teach the existence of two kinds of afterlife: a heaven and a hell. All religions further teach that a good way to find yourself being denied access to heaven is the willful harming or murder of others, usually leading to an eternity of pain and torture in hell. Regardless of what Anna whispered to Mademoiselle, there is no good possible ending for the cult.
• Fridge Logic: The movie seems to want to imply, and most of the audience concluded, that the afterlife must be terrifying or non-existent—upon hearing about it, Madamoiselle commits suicide... but wouldn't the opposite be more likely? Why would she rush off to eternal suffering? Or why would someone so obsessed with the idea of an afterlife and the fear of death kill themselves after finding out there's nothing after death but oblivion?
  • Another possibility is that Anna's testimony to Mademoiselle was incoherent and/or that the afterlife is simply impossible for human minds to understand. If we think about it: Anna was in no healthy state to be giving a succinct, well thought-out description of whatever she saw in her moment of transcendence, and there have been many real-life historical accounts of individuals speaking in a nonsensical manner following moments of religious ecstasy. Also, most religions refrain from giving thorough descriptions of the afterlife—generally referring to it as beyond human comprehension. Thus, it's possible that Mademoiselle extrapolated from Anna's (perhaps incoherent) testimony that her efforts to 'uncover the secrets of the afterlife' via torture were futile. This would explain why she tells one of her subordinates to "keep doubting" his ability to imagine the afterlife, and would also explain why she kills herself: 1) she doesn't want the rest of the cult to know that their whole operation was futile, and 2) she's come to the unfortunate conclusion that the only way to truly learn about the afterlife is to go there oneself and experience it firsthand; with no means of relaying said newfound knowledge back to anyone still alive. It would also fit with Mademoiselle's character as being willing to do literally anything—including brutally murdering and torturing innocent people—in the pursuit of answers.
• How did the family Lucie murders manage to build a state-of-the-art torture basement under their house with nobody noticing or investigating? Possibly Fridge Horror - the cult could be so large and influential that they have enough members skilled in construction to build said torture basement, or so large and influential that they can kill or bribe everyone that would cross them.