Funny who is an “extremist” these days.

Senators Kamala Harris and Mazie Hirono (Democrats of California and Hawaii, respectively) are challenging the nomination of Brian Buescher to the US District Court for Nebraska because he belongs to a religious organization that takes positions they describe as “extreme.” Which organization?

The Knights of Columbus.

KOC, a philanthropic social group founded in 1882, is the world’s largest Catholic fraternal organization. It has 2 million members who have raised more than $1.5 billion for charity in the past decade.

Unlike, say, the University of Notre Dame, the KOC is one of those Catholic organizations that remains, not to put too fine a point on it, Catholic. Which is to say, it affirms Catholic teaching, including Catholic teaching on questions such as marriage, sexuality and abortion. Sen. Hirono says that these “extreme positions” should oblige Buescher to recuse himself from any case touching on the related issues, and both senators have pressured the nominee to resign from the organization entirely.

There are several problems with that. For one, the Constitution explicitly forbids imposing any religious test for public office, which is what Sens. Harris and Hirono here propose to do for the federal judiciary. The second and related issue is that it is not the Knights of Columbus that opposes abortion and same-sex marriage, but the Catholic Church. If a KOC member is ineligible to serve on the federal bench because of the beliefs of that organization, then every Catholic in the United States — and the world, for that matter, all 1.2 billion of them — is ineligible for similar office, since they belong to a much larger and much more prominent organization that is the source of those “extreme positions.”

“Extremism” is a fast-moving target. As evidence of its extremism, the Democrats cite KOC’s support of California’s Proposition 8, a ballot measure that limited marriage to one man and one woman for the purposes of state law. The measure easily won a majority — a majority of California voters. That was in 2008, when young Sen. Barack Obama was running for president as a candidate opposed to same-sex marriage, as indeed was his major Democratic primary opponent, Hillary Rodham Clinton. Somehow, a political view held by Barack Obama and the majority of California voters in 2008 has become the equivalent of al-Qaeda’s program 10 years later — if we are to take Sens. Harris and Hirono seriously.

If the Democrats were more historically literate, they would blush to pursue such an obvious course of bigotry and illiteracy.

Which, of course, we aren’t.

Sen. Harris, in a wondrous display of utter ignorance, demanded of Buescher: “Were you aware that the Knights of Columbus opposed a woman’s right to choose when you joined the organization?” Buescher deserves credit for declining to respond, “Is the pope Catholic?”

But note the classically McCarthyite formulation of the question.

One of the ironies here is that the Knights of Columbus was founded in part to counter such anti-Catholic bigotry, which traditionally has been associated with the Democratic Party and its military arm, the Ku Klux Klan. If the Democrats were more historically literate, they would blush to pursue such an obvious course of bigotry and illiteracy.

But that is politics at the end of 2018: Every political disagreement is a prelude to Nuremberg, every nonconforming thought an invitation to be cast into the outer darkness.

Under the standard articulated by Sens. Harris and Hirono, every Catholic in the United States would be a political suspect and a second-class citizen — and the First Amendment would be in tatters. It would be a return to the 19th century.

For the Democrats, some things never change.