You appear to be suggesting that despite being raised by Lutheran parents, baptized, raised as a Lutheran, engaging in writing about Lutheran theology, if your parents are Juden, conversion is invalid. Or at best temporary, until a Christian doesn't like you. Kind of makes a lie of evangelization, doesn't it.
A Jew can fool even himself for a very long time, but in the end, he can never avoid being a Jew. One of the tasks of gentiles is to make sure of that, though free will determines whether such prodding awareness is good or evil.
There’s an old story-— a Jew flees America to live on the other side of the world. He wasn’t particularly religious but anyway after several years, then decades of the bachelor life devoid of religious observance, he meets a fine Christian woman and wants to get married—but properly. He wants to convert to Christianity. So he calls up the closest rabbi, tells his story, and asks, “How do I officially renounce my Jewishness??” The rabbi answers, “After so many decades with no apparent connection to Judaism, after such spiritual (seeming) atrophy.... you feel there is some cord that still needs cutting? I’m afraid I can’t help you. You’re stuck.”
The point being, once a Jew...
(Note: there may be a “conversion of doubt” necessary in some cases of apostasy, to return to the Jewish fold, and ol’ daddy Marx would not have been called to the Torah after ‘conversion’ to Christianity. But once a Jew....) Karl Marx was Jewish, with the status of “Tinok sh’nishbah,” a kidnapped child— kidnapped away from his heritage. Unfortunately this is the case of most of American Jewry.)
Chutzpah of the Jews— we don’t even believe in the validity of conversion away from Judaism to another religion. Chutzpah!
Didn’t say or suggest Marx’s religious conversion was invalid. Just said IMO he remains an ethnic Jew because, and I guess I have to repeat myself here, being Jewish is more than a religion.