“If you’re a Christian, you shouldn’t see this movie,” Patricia told Eternity.

When Fifty Shades of Grey was first released as a novel in 2012, Patricia read it to be able to identify with more and more women turning up in her sex therapy office talking about it.

“I’ve read it superficially, but it was so badly written it was actually painful to go through it – even apart from the sex context,” she said. And while Patricia does not intend to see the movie, she says she knows enough about the content – and the impact of pornography – to feel comfortable advising against it for others.

“Pornography is about intent: an intention to elicit sexual thoughts and feelings. So there’s no question this film is pornography, just as the book before it. It is fantasy sex.”

Fifty Shades of Grey revolves around a young college student, Anastasia, who is seduced by a “powerful, gorgeous and tormented and insecure billionaire businessman”, Christian Grey.

“In some way, Anastasia’s love for Christian, and the way she sacrifices her purity and lets him do horrible things to her somehow redeems him. In the third book, ‘love’ conquers and his dark soul is redeemed,” says Patricia. If you could hear her speak, you would detect sarcasm.

The film is being released on Valentine’s weekend in the United States, a holiday that is perhaps still a bigger deal there than it is in Australia. Nevertheless, the timing of the release matches the way the film is being marketed similarly to the book, a “must-see movie for romance-hungry women.”

In fact, author of Fifty Shades E.L. James has said in interviews that the story is a “romantic love story”, with sex only one part of that story. The movie will be 50/50 sex scenes versus other scenes, according to director Sam Taylor-Johnson – less sex than is portrayed in the book.

What have we done to ourselves as a society that tying a woman up and beating her till she’s bruised and bleeding is a popular thing to watch?

It’s the type of sex that is of particular concern to Patricia Weerakoon. Fifty Shades has been accused of normalising what Patricia calls “unconventional sexual behaviour”, including bondage, discipline, sadism and masochism (or BDSM).

“It’s about bondage and submission – the man in the story is dominant, the woman submissive to violence and abuse. What have we done to ourselves as a society that tying a woman up and beating her till she’s bruised and bleeding is a popular thing to watch?”

Fifty Shades of Grey is the fifth most popular book of all time, according to a Nielsen BookScan. According to Patricia, the book’s popularity seemed to confirm suspicions among sexologists and psychologists at that time that men like to watch porn while women prefer to read it – reflecting a female fantasy preference that lends itself more to imagination.

However, recent research has suggested that up to a third of internet porn users are female: “We are now seeming more women – and sadly, very young women – who are watching porn too.”

Just as in men, Patricia says the impact of pornography use on women can be devastating to relationships, presenting sex as “anything but a biblical point of view – a good and gracious gift to be shared in a wonderful, mutually-loving and other-focused relationship,” she says. “Porn is nothing like that.”

Patricia fears that women, and in particular young women – she’s spoken with teenagers from age 14 onwards who are watching porn – will begin to accept that their role in a sexual relationship is what they see online, or in Fifty Shades. “When men want sex, more and more young women are willing to be their porn stars. We talk about the raunch culture of women. It’s true. Women have recognised that their body is where their power is. It has become a commodity.”

Patricia has been practicing as a sexologist for decades, across three continents. She says Fifty Shades is a dangerous fantasy for couples.

“If you’re going to get your satisfaction thinking about Christian Grey – this dark, brooding man with a six pack who wanders around all the time with his clothes off, then when you go to bed with your 45-year-old husband with his gut slightly hanging over his trousers, it’s not going to be the most sexual thing in the world. It’ll be harder for you to be turned on by something that is much more normal,” she says.

I fail to see how whipping my partner, or bruising my partner, or putting handcuffs on my partner and tying him or her to the bedpost, is in anyway honouring my partner, or honouring God with my body.

Watching the movie together or getting any ideas from the movie about something to try at home is also a no-go, says Patricia.

“We need to look at any form of sexual behaviour as man and woman in a Christian marriage and think: is this behaviour honouring our relationship? Is it honouring my partner? And is it honouring God? And I fail to see how whipping my partner, or bruising my partner, or putting handcuffs on my partner and tying him or her to the bedpost, is in anyway honouring my partner, or honouring God with my body.”

She warns Christians to stay away from the movie. But more than that, that Christians should actively discourage other Christians – and non-Christians, for that matter – from watching it too.

“If you’re a Christian woman, don’t go see the movie because it’ll mess up your brain… if your desire becomes conditioned by porn and that’s what turns you on, normal sex with a normal, regular guy, isn’t going to do it for you,” she says.

“And let me warn you men out there, if you’re an unmarried man and your Christian sisters-in-Christ are going to build their sexual expectation around this type of example, a perverted fantasy, your chances of marrying one of them and having a healthy sex life are really shot. You’re never going to be Christian Grey.”