How can we explain Jewishness according to Philip Roth's point of view in The Defender of the Faith?

Philip Roth's point of view in The Defender of
the Faith is not illustrated through Grossbart who is a vain, unscrupulous
manipulator who takes advantage of labels that have no meaning for him in order to
attain special treatment and privileges. Roth makes it clear by Grossbart's low and
scurrilous ( href="http://dictionary.reference.com/browse/scurrilous">scurrilous: gross
abusive buffoonery) behavior that Grossbart's Jewishness is as much a sham as a Chinese
egg roll for a Passover Seder meal.

Roth's point of view on
the truth of Jewishness is illustrated through Marx, who hits the marks when it comes to
understanding that sub-divisions, so to speak, of humanity come after--not
before--common humanity. For Roth, as illustrated through Marx, Jewishness puts human
values before special values (e.g., Marx wants what is right "for all of us"); patriotic
values before factional values (e.g., being a good soldier); being a good Jew before
purely personal desires (e.g., unscrupulous privileges that violate the higher orders of
values).