its pretty simple really,
you dont go adding things that are not there... is christmas in there?
Actually, no, its not there. The term Christmas is actually a derivative of two words...."Christ Mass". Anyone familiar with Catholicism knows what "Mass" is.
It is also important to note that it was the RCC that required the recognition of Christs birth to be on Dec 25th. Most will say this is incorrect because the Bible doesnt say when Christ was born. This would also be incorrect. While its true that Christ was not born on Dec 25th, the Bible does in fact explain when Christ was born. You just have to know a little history of the Hebrew Calendar as well as the history of Jewish priestly courses, in this case, the Levitical Courses.