HATEFUL. Clap-trap. Intolerant. Demonised. Offensive. From the Dark Ages.

These are some of the insults hurled around by panellists during a fiery debate on same-sex marriage on Q&A last night.

The verbal sparring began when controversial traditional marriage advocate Katy Faust launched into her reasons for opposing changing Australia’s Marriage Act to allow same-sex couples to tie the knot.

Faust, a US campaigner who was raised in a same-sex household, kicked off the debate when she claimed there had not been enough debate in the US about the harmful effects of children being raised by same-sex parents.

Labor’s Sam Daystari immediately jumped on her comments and accused Faust, who runs a blog and Twitter account called @askthebigot, of having a hateful view.

“I find it very hard to respect your views because I don’t think it comes from a place of love, I think it comes from a place of hate,’ he told the panel. “I worry that so much of your view comes from not really with an issue of marriage, but an issue with homosexuality. You have described it as a lifestyle. You have said homosexuality drives us further away from God.

“I’m sorry, but I think this American evangelical clap-trap is the last thing we need in our debate.”

.@samdastyari finds it hard to respect views coming from a place of hate. We should debate at a higher level #QandA http://t.co/Bf0XrNMinH — ABC Q&A (@QandA) August 17, 2015

His comments sparked this reaction from Spiked Online editor Brendan O’Neill, who launched into his own diatribe about how a debate on tolerance had become intolerant.

“Here’s what freaks me out about gay marriage,” he told the audience. “It presents itself as this kind of liberal civil-rightsy issue, but it has this really ugly intolerant streak to it.

“Anyone who opposes gay marriage is demonised, harassed.”

O’Neill said he felt there was a real “ugly element” to the debate where people who opposed same-sex marriage were ostracised for having a different opinion and used the recent cake shop cases in the US and the UK as examples.

“I think you really see it in this whole cake shop phenomenon,” he said. “This whole thing around the western world where people are going to traditional Christian cake shops and saying to them, ‘hey you, stupid Christian, make this cake for me’ and if they don’t they call the police. There are equality cases, shops have closed down. It’s a 21st Century form of religious persecution. It’s horrendous.”

O’Neill said he thought the reason why Prime Minister Tony Abbott was floundering over what to do was because he felt trapped by the situation.

“I think the reason why Tony Abbott is very defensive on this issue and is errming and ahhing and shifting from the free vote to the not-free vote and all this stuff. He clearly has a problem with gay marriage and he cannot articulate it because we live in a climate where it is not acceptable as we have just seen in Sam’s attack on Katy in calling her hateful and saying she is talking clap-trap. It’s not acceptable to express this sentiment in public life.

“Tony Abbott is now being described as someone from the Dark Ages for believing what humanity has believed for thousands of years. Within the space of a decade something humanity believed in for thousands of years has somehow become a form of bigotry, a form of hate something you’re not allowed to express in public life. That extraordinary shift in intolerance is something all liberals, like me, should be worried about. Gay marriage is not a liberal issue it has a deeply illiberal streak.”

Brendan O'Neill says there is an ugly side to the marriage equality debate in not tolerating those against it #QandA http://t.co/3IqVQ9frjT — ABC Q&A (@QandA) August 17, 2015

The discussion then moved to the issue of parenting with Greens leader Richard Di Natale saying he was concerned the marriage debate had become intertwined with the issue of parenting.

He said studies showed a child does best when raised in a loving household and dismissed Ms Faust’s claims that scientific studies showed it had to be a mother and a father calling them “nonsense” and “rubbish”.

His remark sparked a reaction from Ms Faust who replied: “Oh my, rubbish. well, it’s actually not. Social science has been studying alternative family structure..”

O’Neill interrupted by calling Di Natale’s view as “bigotry, hateful, it’s prejudice”.

Earlier, the panel discussed the recent controversy over the revelation Unions Royal Commissioner Dyson Heydon had accepted an invitation to speak at a Liberal Party function.

While the politicians voiced their party lines, O’Neill labelled the whole affair as a “rubbish scandal”.

He also called for the scrapping of all Royal Commissions.