Certainly this "Merry Xmas, not Happy Holidays" thing is manufactured. That "Christian nation" thing? Thank Jesus that it's not true.
At the core it goes against the unifying idea of all religions: that religion can offer us an inner peace, where instead of remaking the world in our image (and remaking God in our image), we instead resign ourselves to God's will, or the harmony of the universe, and remake our inner lives in peace. The "Merry Xmas" thing represents the kind of political/religious egotism that makes "killing infidels" possible. Who the hell would want to make Jews, Buddhists, Islamic Americans pasty-faced suburban white Christian Republicans in the first place?
Love your neighbor as yourself. You don't get to choose your neighbor.