The waves of progressive enmity directed at Israel during its recent counteroffensive against Hamas started as a low-level frustration. That morphed into an anger that became a white-hot rage with the Jewish state's refusal to succumb. To roll over. To be a good victim. Israel’s success as a modern market economy and military power is its unforgivable sin. It is worth bearing this in mind when we think about the progressive Left and America. More than any other cause or concern — more than abortion or the climate, far more than healthcare or taxes or the infrastructure bill — it is the Israeli-Palestinian conflict that has become the divining rod with which we distinguish between true believers and everyone else. This is because progressives have turned it into an external proxy fight in the identitarian...