Photo: Atessa Moghimi (A24)./A24 Modern-horror cinema’s most heterodox event took place on Saturday night, when two blonde Whitneys and A24 hosted dueling screenings at a multiplex within the southernmost border of Salt Lake City proper. The film was Heretic, directed by Scott Beck and Bryan Woods, about two Church of Jesus Christ of Latter-day Saints missionaries, Sister Barnes (Sophie Thatcher) and Sister Paxton (Chloe East), who knock on the door of a suburban Colorado house one inclement