The Narrator chucks his Bible at Twilight Sparkle's head, knocking her out cold.
When she recovers, she learns about a bipedal race called "Man" and how they fell from perfection, and how the deity known as "God" sent His only Son to die and rise from the dead in order to save them.
Eventually, Twilight reads all there is to read in it, and obsessively insists upon reading it more. The Narrator then adds to her Biblical studies by... What else? Chucking more books at her, of course!

Equestria's government has long kept secrets from the public. From damning prophecies to ancient threats, anything deemed too frightening is kept from the public. And two of Equestria's biggest secrets are about to unfold, throwing Equestria and beyond into utter calamity.
Celestia issues a state of complete pandemic. Welcome to Undead Equestria.