NY Catholics were less likely to vote JFK

[I spent the winter writing songs about getting better]

In Nassau County too, Kennedy got 45% of the vote and the county was more than 25% Jewish at the time (overwhelmingly Democratic).  There must have been at least as many Catholics as Protestants there by 1960.

Some time googling suggests that Nassau was about 45% Catholic at the time.

Source?

It's almost impossible to get reliable precise numbers on religious demographics per county now (ARDA is basically just a rough estimate), much less in 1960.