The coherent community
Folk horror's most powerful element is the isolated community whose beliefs are internally coherent even when externally horrifying. Building this coherence requires genuine imaginative work: understanding why the community believes what it believes, how those beliefs have been transmitted and maintained across generations, what specific conditions (geographical isolation, historical crisis, agricultural dependency) produced this specific moral framework, and why the community members are genuine believers rather than cynical manipulators. The community that makes complete sense from the inside — whose sacrifice of outsiders is genuinely rational given their cosmological framework — is far more frightening than the community that is simply evil. The reader should be able to understand, if not accept, the community's logic.