So are they claiming that Messianic Jews are not actually Jews? Because they implied that people were falsely taking the title Jew if I understood them correctly. That would be the first time I've ever heard that particular assertion.
Yes and that was what I was saying (sorry it wasn't clear).
What it means to be a Jew is complicated. Jews form an ethnicity of interconnected people with a range of beliefs and practices (it is, definitionally, not whether one is religiously adherent to Judaism). To me, one could in principle be religiously Christian and also ethnically Jewish (that's an unusual view among Jews), but to do that requires having an actual connection to the Jewish ethnicity (e.g. if one was raised ethnically Jewish and maintains a Jewish identity). My impression is that "Messianic Jews" are religiously and ethnically Christian who are importing Jewish practices into their otherwise non-Jewish identity. If OP's wife was born Jewish or converted prior becoming a "Messianic Jew," I would stand corrected.
If I, a very white person, start singing songs from Back churches, that doesn't make me Black. I wouldn't face the real-world struggles against racism of Black people, for example, and I think that's a useful hint when thinking about who is and isn't a member of a minority group like Jews. Likewise, acting out Jewish practices doesn't necessarily make one a Jew, and as one example it doesn't subject one to the sorts of anti-Semitism faced by Jews. I'm not saying facing anti-Semitism a necessary or sufficient condition for being a Jew, but if not that, then there must be something else that connects one to the Jewish ethnicity --- the interconnected people who believe they are Jews --- other than just by saying so.
So I'm confused--are you saying that Israel thinks Messianic Jews are not Jews because they abandoned their faith or something like that, OR are you saying that Israel doesn't let Messianic Jews to be citizens because sometimes non-Jews convert to become Messianic Jews?
It sounds like a variation of a - not so much that they abandoned their faith, per-se, but that the faith they espouse as being Jewish is not acceptably ‘in the same room’ as other Jewish faith.
It would be somewhat like saying you were a Messianic Christian because you believed that Mohammed was a later prophet. There is a word for that kind of religion, and it isn’t Christianity.
Israel basically sees them as evangelizing Christians in disguise. They don’t consider them Jewish because they both proselytize and worship Christ as the Messiah. Both of those things are offensive to the traditional tenets of Judaism.