The Queensland Parliament passed legislation on Thursday that lowered the age of consent for anal sex from 18 to 16, in line with vaginal sex, while also removing the term "sodomy" from its criminal code.

Mr Christensen said lowering the legal consenting age for anal sex was akin to legalising older men being able to groom boys.

"I appreciate they wanted to standardise the age of consent for all sort of relationships," he told Fairfax Media.

"But we do know for a fact that there are old men out there who prey on younger men, groom them on the internet and seek to establish sexual relations with them, particularly when they are appear to be questioning their sexuality.

"… I think at 16 years old, when you are questioning your sexuality, when you are going online, when there are predators out there, particularly older men looking for younger boys, this change in the law is fraught with disaster."

Women have been able to legally give their consent for vaginal sex for decades, with Queensland, until Thursday, the only state to differentiate between ages for sex acts.

But the Dawson MP said he did not share the same concerns for young women.

"For fear of being accused of being sexist – let me just say, it would be a great rarity to find a 16-year-old girl who would be willing to sleep with a 50-year-old man," he said.

"Basically, anyone can have sexual relations with a16-year-old – and I am just speaking in general here and stereotyping I suppose, or generalising … I would think that most 16-year-old girls would find it pretty gross to be thinking about having sexual relations with a 40 or 50-year-old man.

"But we do know there are older men, paedophiles, who are attracted to younger men in particular and I just think that if they were going to lower the age of consent - if we are talking about an 18-year-old and a 16-year-old, two guys in a relationship, I don't have any problem.

"… The difference with what's happened has, is that last week, if a parent found out that their 16-year-old son had been having sex with a 50-year-old man, they could have phoned the police and that 50-year-old could have been done for statutory rape, and I think most people would agree – particularly if there is grooming involved and all the rest of it, that is fair enough.

"This week, now it is different, that person gets a free kick from the government."

Mr Christensen's view, aired on social media on Friday morning, and the comments which followed, have been highlighted as examples the "respectful debate" the Turnbull Government is advocating for as part of its same-sex marriage plebiscite policy is impossible.

Mr Christensen said the "untoward language and the vitriol in the debate cuts both ways".

"Whenever I say something which I believe to be nuanced and appropriate, there are all these people out there who are willing to jump online and say all sorts of abuse at me for saying it," he said.

"… If we can't talk about issues like this, the debate around same-sex marriage, what can we talk about?

"Within the same-sex marriage debate, it is almost like if you state any reason why you're opposed to same-sex marriage, you've immediately said something homophobic.

"And if that is the stage of the debate, then basically – the pro side saying there is no debate, just do it – that is just wrong.

"There are a lot of reasons why people are opposed to same-sex marriage.

"I know gay people who are opposed to same-sex marriage – how could they be homophobic?"

Queensland set differing ages of consent in 1990 when the Labor Goss Government decriminalised homosexuality. The law had made it difficult for teenagers, particularly young gay men, from accessing safe sexual practice information, with practitioners forced to inform those seeking information on anal sex about its illegality.

An expert panel assembled by the Annastacia Palaszczuk-led government overwhelming recommended the change earlier this year, as did health, welfare and legal advocates who made submissions to a parliamentary inquiry into the then-proposed law change.

Just 28 of the 42 LNP MPs in Queensland's hung parliament backed the change, with the remainder abstaining.

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