Fox News presenters Megyn Kelly and Bill O’Reilly surprised viewers by arguing that those opposed to equal marriage, including Tony Perkins of the Family Research Council, had no strong arguments against it.

The pair spoke on the O’Reilly Factor, and said that those in favour of equal marriage had a “compelling argument”, and said that opponents to it had not come up with strong enough arguments against it.

Kelly said that “the country’s views are changing” on equal marriage, and that the reason was that proponents of equal marriage had been doing “credible job of making their case”.

Earlier this week, ahead of the start of the US Supreme Court hearings around two equal marriage cases, Tony Perkins, the president of the anti-gay Family Research Council claimed that the court ruling in favour of equal marriage could lead to “revolution”.

Kelly said that, during an interview she conducted, Perkins was unable to “articulate” a “persuasive” argument for why he was opposed to equal marriage.

She said: “What I’m saying is that when you ask, for example, what is it about calling a marriage; calling a gay union a marriage that offends you. How does it hurt a traditional, or a heterosexual marriage? And I didn’t hear anything articulated that was particularly persuasive.”

O’Reilly weighed in to agree with Kelly. He said: “I agree with you a 100%. The compelling argument is on the side of homosexuals. That’s where the compelling argument is. ‘We’re Americans, we just want to be treated like everybody else.'”

He continued: “That’s a compelling argument. And to deny that, you’ve got to have a very strong argument on the other side. And the other side hasn’t been able to do anything but thump the Bible.”

The pair went on to say that religious opponents of measures to legalise marriage equality had also not come up with strong reasons for opposing it.

Kelly said: “Their best argument, thus far, has been, ‘well, marriage is an institution that for 2,000 has been about a man and a woman creating babies.’

“Procreation. But look at how society has changed. I mean, people, they talk today about would we be okay passing a law saying people over 55 can’t get married because they’re not likely to have babies.”

She predicted: “I think the Supreme Court is going to come down on the side of letting the democratic process play out in the states.”

O’Reilly concluded by saying that he supported civil unions, and that he “always” had. He said: “The gay marriage thing, I don’t feel that strongly about it one way or the other. I think the states should do it.”

He said he lived in New York, where equal marriage is legal, and finished by saying: “I want all Americans to be happy, I do.”

Back in January, O’Reilly and Kelly came under heavy criticism for mocking the physical appearance of a transgender prisoner, repeatedly calling her ‘he’ and joking that she wasn’t attractive enough to be in danger of being physically assaulted in prison.

In a second day of landmark hearings, the US Supreme Court will today take on arguments around the Defense of Marriage Act (DOMA), which bans equal marriage across the US.

In yesterday’s hearing, the court heard oral arguments around Proposition 8, the state of California’s 2008 ban on equal marriage, the justices questioned the meaning of marriage, and challenged arguments for the ban.