Saying "Merry Christmas" isn't considered harassment or hate speech. Anywhere.
This notion of religious persecution a certain amount of Christians seem to have is absurd. Especially for trivial things like other people saying "Happy Holidays" or Starbucks having red cups instead of xmas trees or whatever else they had on them.
Just because other people go out of their way to say "Happy Holidays" for the sake of including people who celebrate something different, doesn't mean saying "Merry Christmas" is hate speech.
North America is a very diverse country full of people who celebrate a myriad of holidays in a very short period of time. It's insensitive to assume every stranger you meet shares your religious beliefs, but it isn't a crime.