We used to just wish each other Merry Christmas, and not think anything about it.
But that was exclusionary and insensitive.
So we started to wish each other Happy Holidays. But which holidays? I mean, as well as Christmas, there is Diwali, the Festival of Lights; and Hannukah, the Festival of Lights; and Ramadan, the Festival of Lights; and Kwanzaa, the Festival of Maybe-I'd-Better-Not-Finish-That-Joke.
So I started wishing people a Merry Mid-Winter-Party-Period. And then someone from Australia got offended. (Merry Solstice Party Period is probably safe, but, again, non-specific.)