Cults and religious groups such as Waco and Jonestown served as inspiration.
The asylum in the movie is inspired by Batman in which Gotham City has an asylum named Arkham, an institution for the criminally insane. In the movie, the cult of Apostates; mentally disturbed and animalistic individuals wearing scarecrow-like masks. Scarecrow also appears as one of the rogue villains in the Batman universe.
The movie is based on Jordan Warner's experience with the Evangelical church.
In the middle of production, Jordan Warner took a long hiatus and decided to get inspiration by watching several movies, TV shows and even video games. Among the movies were: War for the Planet of the Apes, Shutter Island, Halloween, The Shining, Eyes Wide Shut, 2001: A Space Odyssey and many others. TV shows were; Waco and Samurai Jack. Video games were: Outlast and The Last of Us.
The movie originally started as a short film, which later transitioned into a feature titled "The War Within." It was about a knight in armor fighting off demons in the spiritual realm. However, the story felt generic and not as impactful. Jordan Warner decided to making it more personal, dealing with themes of trauma and religious PTSD.