Though squeezed by a more vociferous and entrenched right, liberal Zionists have not given up without a fight. They found ways of pushing back, insisting that their two-state Zionism held out the only hope for an end to the conflict and setting up organizations to promote their outlook. J Street in America and Yachad in Britain, founded in 2008 and 2011 respectively, describe themselves as “pro-Israel and pro-peace” and have attracted significant numbers of people who seek a more critical engagement with Israel.

I became an Israeli citizen in 1970, and I am still one today. I worked in the Jewish community in research and philanthropic capacities for 30 years, serving the interests of Jews worldwide. But in the 1980s, I began to rethink my relationship with Israel and Zionism. As recently as 2007, while directing the London-based Institute for Jewish Policy Research, an independent think tank, I still thought that liberal Zionism had a role to play. I believed that by encouraging Diaspora Jews to express reservations about Israeli policy in public, liberal Zionism could influence the Israeli government to change its policies toward the Palestinians.

I still understood its dream of Israel as a moral and just cause, but I judged it anachronistic. The only Zionism of any consequence today is xenophobic and exclusionary, a Jewish ethno-nationalism inspired by religious messianism. It is carrying out an open-ended project of national self-realization to be achieved through colonization and purification of the tribe.

This mind-set blocks any chance Israel might have to become a full-fledged liberal-democratic state, and offers the Palestinians no path to national self-determination, no justice for their expulsion in 1948, nor for the occupation and the denial of their rights. I came to see the notion that liberal Zionism might reverse, or even just restrain, this nationalist juggernaut as fanciful.

I used my position at the think tank to raise questions about Israel’s political path and to initiate a community-wide debate about these issues. Naïve? Probably. I was vilified by the right-wing Jewish establishment, labeled a “self-hating Jew” and faced public calls for me to be sacked. This just confirmed what I already knew about the myopia of Jewish leadership and the intolerance of many British Zionist activists.

Today, neither the destruction wreaked in Gaza nor the disgraceful antics of the anti-democratic forces that are setting Israel’s political agenda have produced a decisive shift in Jewish Diaspora opinion. Beleaguered liberal Zionists still struggle to reconcile their liberalism with their Zionism, but they are increasingly under pressure from Jewish dissenters on the left, like Jewish Voice for Peace, Jews for Justice for Palestinians and Independent Jewish Voices.

Along with many experts, most dissenting groups have long thought that the two-state solution was dead. The collapse of the peace talks being brokered by the American secretary of state, John Kerry, came as no surprise. Then, on July 11, Mr. Netanyahu definitively rejected any possibility of establishing an independent Palestinian state. The Gaza conflict meant, he said, that “there cannot be a situation, under any agreement, in which we relinquish security control of the territory west of the River Jordan” (meaning the West Bank).