Let's consider a completely hypothetical situation.
Let's say your name is Pinchas Ben Schmuel, you're Jewish, obviously, and you're a children's author and illustrator. And you fall in love with a shiksa. Nothing far-fetched so far.
And let's say that shiksa will only marry you if you convert to Christianity. Horrible, we know.
And let's say (again, we're completely hypothetical here) that you're so head over heels for her (she's blonde, and has nice... features, and laughs at 99% of your jokes, and did we mention she's blonde) that you say goodbye to Judaism and hello to Methodism, or Catholicism, or whatever.
Would you (and remember, you're a hypothetical children's author), then write a book about the joys of Hanukkah? No, right? Not as absurd as converting to Christianity in the first place, but a tad hypocritical, isn't it?
Even if that book becomes a best-seller, and a modern classic, how could you look into the blue eyes of your blonde, big-featured shiksa wife and tell her with a straight face that you're committed to Baptism, or Mormonism, or whatever stupid sect of stupid Christianity she made you give up Judaism for?
The answer is, you wouldn't. No Jew in their right mind, hypothetical or not, would convert to Christianity in the first place. But the reverse does happen from time to time. Chris Van Allsburg, for instance. Converted to Judaism for his wife. Attends synagogue. Wears yarmulkes. And THEN wrote "The Polar Express".
Yeah, we don't get it either.