In a politically-motivated op-ed recently scrawled by pundit of supposedly American Jewish values, Dennis Prager, Prager attacks Minnesota Congressman-elect Keith Ellison (who was endorsed in his candidacy by Minnesota’s local Jewish paper) for announcing his intent to be sworn into office over the Koran:

Forgive me, but America should not give a hoot what Keith Ellison’s favorite book is. Insofar as a member of Congress taking an oath to serve America and uphold its values is concerned, America is interested in only one book, the Bible. If you are incapable of taking an oath on that book, don’t serve in Congress. In your personal life, we will fight for your right to prefer any other book. We will even fight for your right to publish cartoons mocking our Bible. But, Mr. Ellison, America, not you, decides on what book its public servants take their oath.

Prager goes on to indirectly compare the Koran to Mein Kampf, asking whether or not Ellison believes it would appropriate for any individual to be sworn in on “their favorite book” as opposed to a book which reflects American values, asserting, without any justification, that Jewish representatives voluntarily swear oaths upon the New Testament. (No representatives are actually sworn in on any religious book, as MJ Rosenberg points out.) Prager also suggests that Ellison is providing comfort to the enemies of America by showing them that Islam can indeed conquer the West.
Among the most reasoned of responses, Eugene Volokh covers the “how un-American” angle, beating Prager’s comments to a Constitutional pulp:

This argument both mistakes the purpose of the oath, and misunderstands the Constitution. In fact, it calls for the violation of some of the Constitution’s multiculturalist provisions.
To begin with, the oath is a religious ritual, both in its origins and its use by the devout today. The oath invokes God as a witness to one’s promise, as a means of making the promise more weighty on the oathtaker’s conscience.
This is why, for instance, the Federal Rules of Evidence, dealing with the related subject of the courtroom oath, state, “Before testifying, every witness shall be required to declare that the witness will testify truthfully, by oath or affirmation administered in a form calculated to awaken the witness’ conscience and impress the witness’ mind with the duty to do so.” If you want the oath to be maximally effective, then it is indeed entirely true that “all that matters is what any individual holds to be his holiest book.” That book is the one that will most impress the oathtaker’s mind with the duty to comply with the oath.
Of course, some might care less about making the oath more effective, and more about using the oath to reinforce traditional American values, in which they include respect for the Bible (the “only … book” “America is interested in”) over other holy books. That, I take it, is part of Prager’s argument, especially when he goes on to say, “When all elected officials take their oaths of office with their hands on the very same book, they all affirm that some unifying value system underlies American civilization.”
Yet this would literally violate the Constitution’s provision that “no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.” For the devout, taking an oath upon a religious book is a religious act. Requiring the performance of a religious act using the holy book of a particular religion is a religious test. If Congress were indeed to take the view that “If you are incapable of taking an oath on that book [the Bible], don’t serve in Congress,” it would be imposing an unconstitutional religious test.

Jeff Weintraub covers the traditional Jewish liberal values angle, somewhat spastically. But it’s not like you really need to be walked through the explanation as to why Prager’s position is bad for Jews in more ways than one.
Perhaps Mr. Prager would have liked to have interfered in the first-ever official Wiccan burial (employing the first ever US government-made pentacle-emblazoned grave marker) for an American soldier killed in Afghanistan, which took place today in Nevada. Because, after all, why should the United States government recognize religions other than Christianity…