Christmas is just a name that's used for it in English. You don't ever pronounce it like Christ the name. There's no point in using another name in a kids movie because then little children might not know it's the same holiday.

In my country the name has nothing to do with Christ. We celebrate Jõulud. Though the tradition itself is older than the name. Meaning the whos can celebrate the exact same holiday with no implication of christ existing if you just switch languages.