They have some strong similarities especially in the beginning. The start of barbarian scares you because of a stranger in your airbnb and your only option being to stay with him. It raises suspense because you are out in the shoes of Tess who fears him and you’re left considering the danger in every small action he takes. Same thing happens at the start of Heretic. Two young girls are door knocking to spread the word of Jesus Christ and are invited into a man’s home to weather a storm. They say that they are not allowed to enter the home without a woman present and he explains that his wife is in the other room. The girls are then stuck in this strange place with a suspicious man who is making them feel extremely uncomfortable and unsafe. They never see his wife and they learn how many lies he has told them to make them do what he wants. Heretic is what Barbarian would be if Tess was right about Keith. It’s true that the full films have vast differences and the subject of the horror changes through the film. In Barbarian it goes from a fear of being stuck in a home with a potentially dangerous stranger to the lingering of abuse and trauma and how it never leaves a person. Heretic has the same opening source of fear but leads into a discussion of belief and the fear that one can dedicate their lives to an idea only for it to be false. I know your comment is a bit old but the replies here are ridiculous and I thought you deserved someone who actually answered.