Greta Berlin, co-founder of the Free Gaza Movement that attempts to breach the arms blockade of the Hamas-ruled territory in Israel, was reportedly in Toronto as part of a cross-Canada tour last week.

While her visit made no media splash, one certainly resulted from her organization’s Twitter account (@freegazaorg), which this week sent a blatantly anti-Semitic message that “Zionists operated the concentration camps and helped murder millions of innocent Jews.”

For many, the pro-Palestinian movement has become a veil for a fundamentally destructive, anti-Israel movement.

In the case of Free Gaza, (which says the tweet was an accident), this is now clearly accompanied by disgusting anti-Semitism.

This is not to say critiques of Israel are inherently anti-Semitic. Israel, like every democracy, is open to criticism for its policy choices.

But the issue here is not one of policy criticism but political activism.

The Gaza flotillas — staged media events that avoid established aid channels — are a prime example of how it’s not really about building up a Palestinian state so much as tearing down the Israeli one.

In defining themselves by a shared enemy rather than a vision for the Palestinian people, such activists forfeit all clarity of purpose.

For instance, on the basic question of how to resolve the conflict, there is total disunity. Two states? One state?

Within the movement there are adherents to either camp.

Last February, anti-Israel activist Norman Finkelstein denounced the refusal of the Boycott Israel campaign to acknowledge Israel’s existential rights: “They won’t mention it because they know it will split the movement, because there’s a large segment of the movement ... which wants to eliminate Israel.” In obsessively trying to isolate Israel through negative publicity, this movement aims to construct a zero-sum equation in which every positive development for Israel is seen as a de facto loss for the Palestinians.

This is why, anti-Israel activists charge Tel Aviv’s gay community with “pink-washing”.

Israel’s record of building a free and tolerant country has nothing to do with the Palestinian national cause, but it is a problem for the anti-Israel effort.

There is logic behind this drive to polarize the debate and raise a false dichotomy The movement is able to win over a small number of anti-Israel adherents (a victory), while ensuring the overall debate appears toxic to the point where a much broader audience is alienated — both from the conversation and Israel (another victory).

Ironically, this only renders genuine Palestinian needs more irrelevant, as exemplified in the movement’s shocking silence toward Hamas’ daily brutalization of the people of Gaza.

Israel’s supporters share a positive, coherent purpose: the peaceful existence of a Jewish state in the ancestral home of the Jewish people.

Our organization has actively fought the zero-sum red herring because our dreams are not contingent on the destruction of the Palestinian cause; indeed, we see no inherent contradiction between Palestinian statehood and Israeli security — as achieved through a peace agreement.

If election season teaches us anything, it’s that there are limits to negative campaigning. Without a meaningful raison d’etre, one may tarnish an opponent’s reputation but will ultimately rally few to one’s camp.

Until pro-Palestinian activists address the corrosive, anti-Israel syndrome within their ranks, they will continue to be dogged by expressions of anti-Semitism, like the one from Free Gaza.