"It might may (sic) no difference, but for [Kentucky] and [West Virginia] can we get someone to ask [Sanders's] belief. Does he believe in a God. He had skated on saying he has a Jewish heritage. I think I read he is an atheist. This could make several points difference with my peeps. My Southern Baptist peeps would draw a big difference between a Jew and an atheist."

That's from an email to colleagues by Brad Marshall, the former chief financial officer of the Democratic National Committee. The email was one of the thousands of internal DNC messages released by Wikileaks on the eve of the Democratic National Convention. It shows that Marshall, who resigned over the email, was trying to use Bernie Sanders's religious beliefs against him in Democratic primary elections—despite representations by the DNC that it was neutral in the competition between Sanders and Hillary Clinton.

On 60 Minutes, Clinton was read the passage quoted above, and asked for her response. She said, "I am adamantly opposed to anyone bringing religion into our political process. I mean, the Constitution says 'no religious test,' so that is just absolutely wrong and unacceptable."

Clinton was referring to Article VI Clause 3 of the Constitution, which says that "no religious Test shall ever be required as a Qualification to any office or public trust under the United States." During the ratification debates the clause drew opposition because it would allow, as critics identified them, "Jews," "Turks," "Infidels," "heathens," and "Roman Catholics" to serve in the national government. There were some who objected to that prospect, who wanted religion—their religion—to be a qualification for office. But of course that view did not prevail. National offices thus were opened to all Americans.

The clause left the states free to impose religious tests, if they so desired. All of them did. Only Christians could serve, or, in some states, only Protestants. Few of these limitations endured, however, and those that did were rarely enforced.

Eventually, in 1961, the Supreme Court took up the question of whether a state may require a religious test for office. At issue was a provision in the Maryland Constitution requiring public officials to profess a belief in God. In Torcaso v. Watkins the Court struck down the provision, grounding its decision not in the religious test clause, but in the establishment and free exercise clauses of the First Amendment, both of which the Court had applied to the states in the 1940s. Torcaso meant that there could be no religious test for any public office in the United States.

Still today there has not been a judicial decision interpreting and applying the religious test ban. Yet it has political force, as Marshall's resignation illustrates. Marshall wanted to "get someone to ask" Sanders whether "he believes in a God" so that he could use what he thought would be Sanders's answer against him in key primaries. Marshall didn't "violate" the Religious Test clause if only because the DNC is a private entity. But his email was at odds with the ideal that the clause promotes—of a politics that is religiously inclusive and tolerant.