tzippi, that is literally true but seriously misleading. The issue is what phrase people use in another language to be the functional equivalent of the English phrase “Merry Christmas.” You would have us believe that “Feliz Navidad” means “Happy Nativity.” I’m sorry, but that’s nonsense.
Look up “navidad” in a Spanish-English dictionary. Here, I did it for you:
http://www.wordreference.com/es/en/translation.asp?spen=navidad
“Navidad” is the Spanish word for “Christmas.”
Mir darf vissen vie azoi tzu redden. How’s that for an explanation?