Better than I remember, but as far as the folk horror unholy trinity goes, The Wicker Man is unrivalled and Witchfinder General and The Blood on Satan's Claw trail behind.
Witchfinder General explores witchcraft and religious debauchery during the Civil War, but not to the same extent as the much earlier folk horror outing Häxan. In terms of thematics and imagery it doesn't quite measure up to Black Sunday, nor does it compare to the gorey medieval punishment prevalent in Mark of the Devil. Nonetheless, historical underpinnings are certainly present in Witchfinder General and the costuming and set pieces in particular suitably replicate the era.
More than anything, the pacing prevents this from being one of my favourites within the folk horror niché. Frustratingly, a large portion of the runtime centers around Vincent Price gallivanting around the countryside via horseback. Poor horse, having to lug all 6' 4" of Vincent Price around for the whole damn film.