Of course, when we talk about diversity on the court, no one is worried that the lone Protestant--Justice John Paul Stevens--will feel isolated, that he'll offer the sense of complaint that Justices Sandra Day O'Connor and Ruth Bader Ginsburg did that there weren't more women on the court. Likewise, no one is complaining about there being two Jews on the court, far in excess of their number in the general population. When Herbert Hoover nominated Benjamin Cardozo there was widespread complaint about two Jews on the court. Now, no one would think that that was wrong.
So is it sheer quota mongering for there to be concern about the lack of Hispanics or Asians or women on the Court? I don't think so. There's a difference between minorities who feel oppressed and those that don't. Having one Protestant on the court is qualitatively different than having one woman or one Hispanic. That wasn't always the case when the country was riven between Protestants and Catholics.
In our own time these differnces have mattered in ironic ways. Antonin Scalia has railed against racial preferences and he's made strong arguments against them. But it's worth remembering that he was confirmedin 1986 it was by 98-0. Senators who voted against Robert Bork or even David Souter granted deference to Scalia. Part of it was because Democrats trained their guns on WIlliam Rehnquist who was being nominated to Chief Justice. But Scalia also got a free ride because he was the first Italian-American justice. His hard-right philosophy was overlooked because of his ethnicity. If that's not affirmative action, I'm not sure what is.
This article available online at:
http://www.theatlantic.com/politics/archive/2009/07/scalia-sotmayor-and-the-protestant-rebellion-that-wasnt/21376/