I answered this a bit in the other thread...but I'll go again.
mandalinn is right, there are many holidays in the month of December. She listed them all for you already.
There has been a recent uproar recently about different stores using the term "holiday tree" and not Christmas tree in their ads, as well as the term "Happy Holidays" instead of saying Christmas..and people have been getting upset about it. Actually, I find this very interesting, because the tradition of decorating an evergreen tree in the winter actually came from Pagan traditions-Yule/Winter Solstice, NOT from Christianity. When Christmas started being celebrated in the month of December, and his resurrection started being celebrated in the spring, these dates were actually chosen purposely to "replace" the Pagan holidays (Winter Solstice and Ostara/Eostre)-rather than during the times that those events actually happened.
It was basically done on purpose by certain rulers...but I won't get into all that.
In fact, the date of "Easter" still goes by the phases of the moon, in Pagan tradition, rather than the same date every year. It even has kept the Pagan name-with a slight spelling change.
Red and green, cranberry dishes, ham, evergreen decorations-all of these things come from Yule/Winter Solstice. Other than crosses and nativity scenes...most of the Christmas decorations and traditions people do today have nothing to do with the birth of Christ or his rebirth at all.