Joseph Massad, of Columbia University, has an article (based on a recent speech he made) in Electronic Intifada that claims - like many antisemites do - that Ashkenazic Jews aren't really Jews. But I'm not sure if he is espousing the discredited Khazar theory, or something different:
It is true that both Judaism and Christianity are Palestinian religions. It is also an established historical fact that the inhabitants of what came to be called “Europe” later, whether Christians or Jews, had converted to these Palestinian religions centuries after the Palestinians had.
It is also true that these new Christians of what would become Europe never thought of themselves as direct descendants of the ancient Palestinian Christians who spoke Aramaic, but saw themselves correctly as more recent converts to this Palestinian religion.
Yet these same Christian converts often insisted that converts to Judaism in what would become Europe were somehow descendants of the ancient Palestinian Hebrews who also spoke Aramaic at the time of the so-called Roman expulsion of the first century.
This was important because these converts to Christianity accused the converts to Judaism of killing the Palestinian Christ.
There is a lot of nonsense here, like calling Judaism and Christianity "Palestinian religions." That is an obvious attempt to claim some sort of special status for Palestinians today who have no relationship whatsoever with the biblical Land of Israel that is indeed the origin of both religions (and of course Islam is also modeled in no small part on Judaism.)
Mossad's flat assertion that Jews in Europe were converts is not footnoted so I cannot be sure which nonsense he is pushing. Outside the Khazar theory, there was a genetic study in 2013 that claimed that the matrilineal line of most Ashkenazic Jews came from women who converted to Judaism in Europe.
However, even that study was controversial and a more recent study shows that the women actually were from the Near East. And genetic studies of the patrilineal line have been almost unanimous in showing that Ashkenazic Jewish men also have origins in the Near East. Beyond that, a genetic linkage study of all Jews, Ashkenazic and Mizrahi, found them to be related and concluded "the most parsimonious explanation for these observations is a common genetic origin, which is consistent with an historical formulation of the Jewish people as descending from ancient Hebrew and Israelite residents of the Levant." Wikipedia has a fine roundup of the studies.
So Massad is a liar. His calling his lies an "established historical fact" is a bullying tactic to make anyone who disagrees pause - thinking that certainly a professor at Columbia wouldn't lie so blatantly. This is only one part of his writing where he is "thinking past the sale" - he wants to make it look like his assumptions for his hateful theories are "established facts" so that while you are thinking about his theories, he has already made you subconsciously believe that his assumptions are accurate.
Massad's lies are not innocent. He chooses his lies to be consistent with his anti-Israel, pro-Palestinian political beliefs (hence characterizing Judaism as a "Palestinian" religion.) And he couches them as "facts" in such a way that it takes time and effort to dissect his words to show how hollow his actual argument is.
I don't even have the time or the energy to refute Massad's other claims. (He circles back to his claim that the original Zionists were antisemites, for example.)
When the foundation of his argument is a lie, and one that is so easily disproven yet he insists is true without providing an iota of evidence, then he has already proven once again that he isn't interested in the academic pursuit of knowledge but in anti-Israel propaganda.
Columbia is right to allow all opinions to flourish on campus. It is not right to allow its professors to spout lies in a larger effort to radicalize students against Jews who believe in their right of self determination.