My son Daniel pointed out to me a feature of Trump’s speech to the laughably named Values Voters summit which seems to have slipped by most observers. As summarized by Colbert King in the Washington Post
Telling a revved-up Values Voter audience that he is “stopping cold the attacks on Judeo-Christian values,” Trump suggested to the crowd, which already thinks a “war on Christianity” is being waged, that invoking “Merry Christmas” is a way of fighting back.
But “Happy Holidays” is exactly an expression of Judaeo-Christian values, coined to embrace the Jewish Hanukkah as well as Christmas. In this context, King’s suggestion that “Happy Holidays” is secular misses the point. The majority of secular Americans celebrate Christmas (happily mixing Santa Claus, carols, and consumerism). They say “Happy Holidays” as a nod to religious diversity among believers, not because they feel excluded from Christmas.
Insistence on “Merry Christmas”, by contrast, is a repudiation of the claim implicit in “Judaeo-Christian”, namely, that Jews and Christians have essentially the same beliefs and worship the same god, and that the differences between the two are ultimately less important than the commonalities. On any interpretation of Christianity in which all who reject Christ (including, I imagine, most of us here at CT) are damned, “Judaeo-Christian” is a much more pernicious version of political correctness than “Happy Holidays”.
I haven’t got to a proper analysis of this, so I’ll turn it over to commenters.