Based upon my own experiences, growing up Jewish in New York City (born in 1948), I would like to add the following:
The vast proportion of Jews emigrated to The United States in the first twenty years of the 1900's. They were uniformly poor, but, like the latter-day immigrants from Asia, placed a high value upon education and hard work. These Jews learned English and became citizens.
Juat as they were becoming true Americans, The Great Depression hit. In FDR, they saw a father figure, and believed that his liberal social policies saved them from destitution. This belief was passed down to the next two generations, many of whom still are reflexively liberal, despite achieving financial successes more generally associated with self-reliance and conservatism.
The hero-worship of FDR was transferred in great measure towards JFK, and his assassination cemented the "democrat-for-life" attitude already prevalent in the Jewish community. Jews and Blacks have been voting that way for generations, and refuse to consider facts that might sway them from their pseudo-religious liberalism.
Any Americans who have a hard time believing the strong draw of fundamental Islam need only to look in their own past.
Without thinking, knee jerk acceptance of an ideology is universal around the world.
That's good thinking, and something I've argued as well. Prior to the FDR period, Jews were heavily Republican. In fact, the earliest Jews elected were Southern Republicans. But, as you said, that began to change with the next wave of Jewish immigraiton in the 19teens and 1920s.