A Catholic cardinal who is supporting a lawsuit against the Obama administration's mandate that all health insurance cover female contraceptives refused on Sunday to say whether presumptive Republican presidential nominee Mitt Romney was a Christian.

During an interview on Fox News, host Chris Wallace asked Cardinal Donald Wuerl if Mormons were "true Christians."

"I never get into defining other people," Wuerl explained. "I define myself. That's one of the reasons, by the way, why we are in court."

"I don't want the president to define me so I'm not going to define somebody else."

Throughout his campaign, Romney has been dogged by the accusation by some evangelical Christians that faith was really a "cult."

Those accusations echo concerns that evangelical Christians also had about Catholicism while John F. Kennedy was running for president in 1960.

"Catholics in America faced perils virtually since the beginning of the republic," Columbia University Professor of History Alan Brinkley recently wrote. "They experienced Protestant fears of the Vatican and the pope. They have struggled against the belief that Catholicism was something close to a secret cult."

"In 1960, this fear threatened the campaign of John F. Kennedy – the first and still only Catholic president. Everywhere he went, Catholicism dogged Kennedy’s path."

Watch this video from Fox News' Fox News Sunday, broadcast May 27, 2012.