Norman Podhoretz raises the question in a Wall Street Journal op-ed.

He suggests an answer by observing that non-observant Jews are the most likely to vote Democrat, while those few Jews who are Republican tend to be Orthodox. In other words, an inverse relationship between religious practice and support for Democrats. Therefore, he suggests, modern liberalism may function as a religion for "secular" Jews.

A similar observation may be made for Roman Catholics. Those who attend mass infrequently are more likely to vote Democrat.