As I created a recent cartoon, it occurred to me that the people who say "As a Jew, I condemn Israel for X" are, in fact, promoting antisemitism.
The entire point of saying "As a Jew" is to place oneself into a position of moral superiority - compared to other Jews who do not share the same pseudo-morality of the speaker.
This gives their non-Jewish audience the idea that there are good "As a Jews" and the other, vast majority of Jews who do not share their hate of Israel are by definition immoral.
This mirrors the distinction made by John Mearsheimer between what he called "righteous Jews" and "New Afrikaners." His "righteous Jews" were those who can find no redeeming value in Israel:
Righteous Jews have a powerful attachment to core liberal values. They believe that individual rights matter greatly and that they are universal, which means they apply equally to Jews and Palestinians. They could never support an apartheid Israel. They also understand that the Palestinians paid an enormous price to make it possible to create Israel in 1948. Moreover, they recognize the pain and suffering that Israel has inflicted on the Palestinians in the Occupied Territories since 1967. Finally, most righteous Jews believe that the Palestinians deserve a viable state of their own, just as the Jews deserve their own state. In essence, they believe that self-determination applies to Palestinians as well as Jews, and that the two-state solution is the best way to achieve that end. Some righteous Jews, however, favor a democratic bi-national state over the two-state solution.
To give you a better sense of what I mean when I use the term righteous Jews, let me give you some names of people and organizations that I would put in this category. The list would include Noam Chomsky, Roger Cohen, Richard Falk, Norman Finkelstein, Tony Judt, Tony Karon, Naomi Klein, MJ Rosenberg, Sara Roy, and Philip Weiss of Mondoweiss fame, just to name a few. I would also include many of the individuals associated with J Street and everyone associated with Jewish Voice for Peace, as well as distinguished international figures such as Judge Richard Goldstone. Furthermore, I would apply the label to the many American Jews who work for different human rights organizations, such as Kenneth Roth of Human Rights Watch.
This is a pretty good list of "As a Jews." Notice that none of them seem to actually live in Israel and would have to live with the consequences of their policy prescriptions.
The Jews who actually support Israel and who disagree with calling it an apartheid state - including virtually all Israeli Jews - are the evil "New Afrikaners." (The idea that Zionists would be against an Israel that truly practiced apartheid is not even considered by Mearsheimer, who is of course the archetypical "As a Jew"/"Righteous Jew.")
The people who style themselves as the "righteous Jews" are sending a clear message - the other Jews, Jews who actually believe that Jews have a right to self determination, are immoral.
It is only a small step beyond that to be telling the world that only one kind of Jew deserves to be treated with respect and as a human being. The other type supports apartheid, oppression, murdering innocent children and all manner of war crimes - and when they get blown up and stabbed by the good oppressed Palestinians, they somehow deserve it.
When a Jew says "As a Jew," he is signaling to the world that the "other" Jews deserve to be hated. That is pure antisemitism.