There have always been a lot of Jewish intellectuals throughout history. Unfortunately, over the past two centuries, being an intellectual has become synonymous with embracing socialism, which is atheistic.
There's a lot of Jews who are torn between being proud of their intellectual lineage (from Spinozza to Einstein)and wanting to be viewed as thoroughly modern thinkers, which means rejecting religion.
It's sort of like cutting off your nose to spite your face.
In Eastern Europe where the majority of Jews lived 100 years ago there was various levels of observance. However , the proportion of fervently religious was significantly greater than now in America.
Unfortunately whne many Jews came to America in the Ellis Island era, very few of those very observant came. Basically the least observant came at that wave and the current American Orthodox community is largely the survivors of Hitler.
The former are liberal irreligious and marched for civil rights but didn't rally against Hitler or for Israel.
The latter are the opposite.
The fromer voted for Gore the latter for Bush