For some reason, Democrats love to ask President Trump's judicial nominees about their religious backgrounds. Sen. Ben Sasse (R-NE) was worried that U.S. district judge Peter Phipps, nominated to serve on the Third Circuit Court of Appeals, would be no exception. So, he launched a preemptive strike at Wednesday's Senate Judiciary Committee hearing and asked Phipps about his membership in the Knights of Columbus (KoC), a Catholic fraternal organization, and whether it has anything to do with his nomination. After all, Democrats have obsessed over the group in recent years.

Sen. Ben Sasse (R-NE) admitted to being puzzled such line of questioning.

“Judge, did you get questions for the record about being a member of the Knights of Columbus?” Sasse asked. “This is a new tradition around here evidently, trying to figure out if people are members of religious organizations.”

"Yes, associated with my district court nomination," Phipps acknowledged. He said he does "not" know why.

Sasse described the Knights of Columbus as a harmless organization that organizes "community service...fish fries, and pool parties," leading him to pose a more humorous inquiry.

"Are you now or have you ever been involved in the organization of a fish fry?”

The witness laughed. Yet, Democrats' religious litmus tests are far from funny. Two years ago, Sen. Dianne Feinstein (D-CA) asked Trump's 7th Circuit Court of Appeals nominee, Amy Coney Barrett, quite pointedly, "Are you an orthodox Catholic?" Having read some of Barrett's writings on abortion and the death penalty, Feinstein shared her concerns.

"The dogma lives loudly within you," the senator said.

WATCH: Sen. Feinstein to appeals court nominee Amy Barrett, @NotreDame law prof/#Catholic mother of 7: "The dogma lives loudly within you." pic.twitter.com/mpDgNZGRsa — Jason Calvi (@JasonCalvi) September 6, 2017

Feinstein also warned then-Supreme Court Nominee Neil Gorsuch during his confirmation hearings that his faith cannot get in the way of "super precedent" Roe v. Wade. Gorsuch repeatedly explained to her that the Constitution, not his personal opinions, is his guide in court.

Barrett was eventually confirmed, as was Gorsuch.

A few of the Democrats who heard Sasse's questions were offended by his accusations.

“To be clear, no senator on the Democratic side has ever suggested that a member of any organization is per se unfit for the bench, only those who cannot be fair and impartial,” said Sen. Mazie Hirono (D-HI).

But, National Review called her bluff. Just a few months back, Hirono told judicial nominee Brian Buescher she was worried about his relationship with KoC.

"The Knights of Columbus has taken a number of extreme positions," Hirono said before asking the nominee to promise to "end" his membership with this organization "to avoid any appearance of bias."

Others members on the Judiciary panel on Wednesday questioned Phipps's supposed lack of experience, but by most observers he seems primed for committee approval.