You don't get to have it both ways, either you get to live within your "nothing sacred" claims or you can abandon them but you don't get to pretend you really believe nothing is sacred when it suits you and then to claim what you want to - temporarily - assert something is to be temporarily held to be sacred as you vent for show.
And since post-literate levels of reading comprehension would seem to be a major contributing factor to the current form of atheism, let me point out that the reason Keillor had to invent that absurd example - OF THE KIND OF THING HE WAS OPPOSING - is because Christians don't write disrespectful, jokey songs diminishing the Jewish Holy Days. I've never come across anything that could serve as an example of that. I can't imagine anyone doing that, if you can find an example, send it to me and I'll comment.
I read online that approximately half of the top of the pop-chart Christmas songs are written by Jewish songwriters, some of them not half-bad as pop songs but none of them exactly Christian in content. I can say that my all time most hated Christmas pop song, ever, which I absolutely hate Have Yourself a Merry Little Christmas seems to be the product of gentile Hollywood song hacks.
I haven't seen anything definitive but looking up that bit of trivia, I did find out that the long told story of the composer of one of the most popular of the serious Christian content Christmas songs, O Holy Night, Cantique de Noël, that Adolphe Adam was Jewish and that the Archbishop of Paris wanted the song suppressed for that reason, would seem to be a myth. From what I've read someone who was writing on the topic for a dissertation tried to find confirmation that Adam was Jewish and couldn't find any, including that none of the people who knew Adam seems to have identified him as Jewish, as didn't the Nazis when they were compiling anti-semitic reference books about music. I haven't read deeply on the subject but if that's true then how the myth got started and spread is more interesting than the myth, itself. It's kind of disappointing if it's not true that he was Jewish. I liked the irony. If I can be excused for using the "i" word.
It was thrilling, last year, to find the recording of the great, great late 19th century- earliest 20th century French bass, Pol Plaçon singing it because he would almost certainly have known how Adam would have expected to hear it sung.
One thing is absolutely certain, the first Christmas song, the most often sung, the most widely sung, from even before Christmas was part of the official church calendar, the most translated, most often set Christmas song was composed and sung by a Jew, the mother of one of the most famous of all Jews, Mary the mother of Jesus, whose birth is what Christmas is all about, the occasion of her composing My Soul Doth Magnify The Lord. The entire content of it is absolutely saturated with Jewish content, the original Christmas song is a Jewish song. You can hear that passage from Isaiah reflected in what it says about the powerful being thrown down from their high seats, the poor being filled with good things and the rich sent away empty. I really love this simple setting by George Dyson, Freeman Dyson's father who was an Anglican church composer.
I know Dyson expected it to be sung by boys' voices but it would be nice to hear it sung by Mary's fellow women. We really need either a gender neutral or a female equivalent of "fellow" for just such statements .