Image via WikipediaWhy am I wishing all a Merry Christmas? Well it's not because I suddenly believe in Christmas. It is because it is Christmas day and it is appropriate to say Merry Christmas, at least to Christians. Likewise it is appropriate to say Happy Hannukah or Ramadan Kareem on their respective holidays.
Christmas is a day and not a season so the only time it should be appropriate to say Merry Christmas is on Christmas day. We don't go around saying Happy Easter for weeks or months prior. Nor do we say Happy Thanksgiving, Happy Fourth of July or Viva Cinco de Mayo for weeks or months prior.
If there is any real "War on Christmas" it is over the complete hijacking of the months of November and December as "Christmas".