If someone is giving you a hard time for wishing them a Merry Christmas...then they are being too hard and jerky. It's not that everyone else doesn't think you can say it.
I try to tailor my wishes to the person. I don't personally celebrate Christmas in my home (we do go to my mom and dad's house to celebrate it with them though) as I am not a Christian, but if I know someone celebrates Christmas, or it is Christmas (as in December 24th or 25th) then I will say Merry Christmas to people proactively. If I know someone celebrates Chanukah, I will tell them Happy Chanukah proactively. Ditto Solstice. If someone says "Merry Christmas" or "Happy Chanukah" or "Happy Solstice" to me, I will say the same back to them. None of that is offensive to me.
If I don't know what someone celebrates, I just say Happy Holidays, and what I mean is "Whatever you celebrate, be it Christmas, or Chanukah, or Festivus, or whatever, have a great one." I don't understand how any of these well wishes are offensive. People need to lighten up.
Again, I truly believe that the whole "Happy Holidays" thing is in no way meant (by the vast majority of people) to put anyone down. It's just trying to include as many people as they can because there are other holidays celebrated by other people during that same time period. I don't see how that makes "Christmas" some sort of dirty word.
Bonita~Do you mean public place like a school, town hall, fire station etc?