I feel like that's a very gradual gradient. Is it only when Christmas is a fundamental part of the story?
For example your comment makes me think of the "Die Hard isn't a Christmas movie" people, but it would have been a completely different movie if not for the office Christmas party.
I'm pretty sure the "there's snow, there's a Christmas tree, this is a Christmas movie!" is a joke though. I haven't ever done this joke myself. I guess still need to find what in Die Hard makes it a Christmas movie :) .
it's Christmas eve, part of the premise is a dude returning home t family for Christmas, there's a Christmas miracle (that he survives at all), the villain is after material gain and is about to ruin Christmas, and John's wife's name is fucking Holly! What more do you want‽
I can only assume you're too young to have gotten around to it because I can't imagine anyone my age (older millennial) possibly being able to avoid seeing it even on purpose.