There's a lot of garbage bouncing around the net about the 'War on Christmas' which does seem to be a real thing but only for ultra-sensitive Christians and a very few atheist activists. In day to day terms this war seems to consist of substituting “Happy Holidays” for “Merry Christmas”, some people are happier to say the former because they don't celebrate Christmas themselves or they don't know whether the person they are talking to does so.

Some atheist groups have put up billboards and adverts pointing out that Jesus is not the reason for the season and he isn't, the winter holiday is a much older tradition based on the winter solstice (21st December this year), the day on which the sun is at its highest point in our sky, the reason is the axial tilt of the earth which is a real thing.

Jesus is also not the reason we have Christmas trees, that's a pagan tradition, Father Christmas or Santa Claus is a combination of a number of Scandinavian myths and a lot of commercial intervention.  You can call the holiday 'Yuletide' and you'd be correct, you can call it 'Holiday' if you like or 'Jul', 'Ziemassvētki', 'Saturnalia', 'Koleda', 'Hanuka', 'Kwanza' or 'Eide al Majeed'.  You can celebrate the birth of Mythra instead of Jesus, both births, and those of many other deities/avatars were conveniently relocated to match the winter solstice. Exchanging gifts, gathering the family together, giving to the needy, good will to all mankind – nothing to do with Jesus.

In short Christmas is a global, mythological mash-up and I really don't give a shit what you're celebrating as long as people are nice to each other for a change.  It just happens that I grew up in a supposedly Christian country so 'Christmas' is what I call it.  Merry Christmas.