Yes, ab, I know, but it's the same festival whatever it's called and the winter festival existed before Christians called it Christ's Mass and told a new story about its meaning. They did the same with the Spring festival that we now call Easter, and Hallowe'en amd several other things. I'm not complaining, just repeating what are given as historical facts by people who have done the relevant research.
My point is simply that people can, and do, and always have, made Christmas mean whatever they like. So if Christmas means the Simpsons to someone that's allright however weird some of us may think it.