When the world comes down with a plague that brings the inner demon out of ponies, it becomes a fight for survival where love, faith, harmony and innocence is forgotten. But one mare fights for one of these things: Faith. Faith is the God of Belief, and she believes she can cleanse this world of infected abominations, one bullet at a time.

ANTHROPOMORPHIC

(If you want a sort of theme song this is the song:
The Preacher - Jamie N Commons)