Progressive Jews who have spent years supporting racial equity, gay and transgender rights, abortion rights and other causes on the American left — including opposing Israeli policies in Gaza and the West Bank — are suddenly feeling abandoned by those who they long thought of as allies. This wartime shift represents a fundamental break within a liberal coalition that has long powered the Democratic Party. In Los Angeles, Rabbi Sharon Brous, a well-known progressive activist who regularly criticizes the Israeli government, described from the pulpit her horror and feelings of “existential loneliness,” her voice breaking. “The clear message from many...