Why are Christmas horror movies a thing? Yes, horror is a pretty large genre and you could theoretically make a horror movie about anything, set during any time of the year and, with the right writing, acting and directing, it will be scary. My confusion comes from where the desire to make Christmas, or anything taking place during that particular season, scary.
For me, when I see a horror movie trailer with lame taglines lines like "Jingle bells, Jingle Hell" I wonder what drunk moron came up with that. Then, I decide that movie's probably going to be stupid and decide not to see it.
See, for me there's a weird tonal dissonance between the horror genre and the holiday season in general. They don't really combine well to create fear. Horror movies that take place in October don't have that problem. The setting, being around Halloween, adds oomph to the plot and ups the scary factor. Horror films that are set in remote areas, same thing. The setting lends legitimacy to making me think its a "real" horror movie.
Christmas and horror, not so much. There are plenty of horror films that take place in the winter, but the movies I'm thinking of always feel the need to combine horror specifically with Christmas. Someone's murdering guests at a holiday Christmas party. There's a serial killer who dresses up as Santa to commit his crimes. The fact that "Santa" is killing people completely takes me out of the story. I can't suspend my disbelief that much.
So, that's my view about holiday-themed horror, what's yours?