'Heretic's intense ending, explained

If you've seen Heretic, chances are high you'll never see Hugh Grant the same way again. This ominous, brazenly academic, and complex A24 horror film from co-writers/co-directors Scott Beck and Bryan Woods (A Quiet Place) quite literally traps you in a maze of unspoken threat, religious debate, and blueberry pie, with Grant's horribly hospitable Mr. Reed proving one of the more surprising villains in modern horror.SEE ALSO:What to watch: Best scary movies
But how about that ending? What act