Just roll with it. I wish people a Merry Christmas and smile and don't respond if it doesn't work for them
I feel this is the best way. If they don't like you saying Merry Christmas, that's their issue, not ours. But if they do, often you'll see their faces sigh in relief.
Shame the season has come to this, but I refuse to change for a minority. Christmas is about Christ our Lord.
But conflict over this is silly. Good move, Bill.