We must begin by trying to define Judaism and the Jewish people, no easy task even for one who has spent a lifetime studying Jewish history. Worlds like religious and secular and nationalistic, which have clear-cut meanings in other contexts, become fuzzy and confused when applied to us. The plain fact is that we Jews almost defy definition. We are a unique demographic group; none of the customary sociological categories is a perfect fit for us.
We are a religious group, true, but simultaneously more than that. We share some facets of national existence, but not all of us partake of them fully. We are an ethnic entity, yet at the same time an admixture of many races. If we are to be defined with any measure of accuracy, a new term must be devised, peculiarly and uniquely for us.
Roland B. Gittelsohn, Partners in Destiny: Reform Judaism and Zionism (New York: Union of American Hebrew Congregations, 1984), 1.