Thousands of people congregated yesterday on the North Carolina capital, Raleigh, to demonstrate and counter-demonstrate against and for the so-called 'bathroom law' which requires transgender people to use public lavatories appropriate to the gender on their birth certificate. It's an issue that has polarised opinion and had huge consequences for the state. Major businesses have come out in opposition to it including PayPal, Wells Fargo, Dow Chemical and Marriott International. President Obama has criticised it, entertainers have said they won't perform, conferences have been cancelled and the state has taken a huge pummelling.

On the other hand, retailer Target, which announced that transgender employees and customers would be allowed to use the bathroom that corresponds to their "gender identity", has been hit by a boycott and a petition which has raised half a million signatures. North Carolina isn't the only state to face this issue, but it's in the news at the moment.

Something tells me there's nothing simple about this.

You're absolutely right. Conservative Christians like the Alliance Defending Freedom are all in favour of the law. The minister of Global Vision Bible Church, Pastor Greg Locke, posted a video on Facebook accusing Target of opening the door to perverts; it was shared more than 265,000 times. On the other hand eight United Methodist bishops have issued a statement calling for the repeal of the law and referring to the "hurried passage" of the bill. It says the state has become "increasingly divisive" and calls on United Methodists "to cultivate community that is welcoming and nurturing to all people" and "not add to the increasing levels of fear, suspicion and divisiveness in our state and our nation". It's also become a political football: Donald Trump has come out against it, while Ted Cruz is for it.

Was the bill really passed in a hurry? 

Yes. It was passed in response to a local ordinance passed by the Charlotte City Council on February 22 prohibiting discrimination on the basis of sexual orientation or gender identity. Opponents claimed the bill was poorly drafted and would let people of one sex use lavatories earmarked for the other. The state legislature passed House Bill 2, insisting people use facilities corresponding to what's on their birth certificate, on March 23; it was passed by both houses and signed into law by the governor, Pat McCrory, on the same day. On the other hand, critics say the whole thing is pointless because such local ordinances are already unconstitutional under North Carolina law.

That is very quick. They must have been seriously worried. But – sorry if I'm not keeping up, here – what exactly were they worried about?

Several things. Supporters of the bill say there are issues of privacy, in that young girls, for example, shouldn't have to feel uncomfortable about using facilities in the presence of biological males. They also argue that removing this protection – as Target has done – would open the door to male predators who could use it as an excuse to invade a space in which women ought to be able to feel safe. Peter Sprigg from the conservative Family Research Council says: "The government should never purposefully threaten the public safety of women and children by creating the legitimized access that sexual predators tend to seek." He also argues: "It would be impossible for a young girl to determine whether or not the man in the restroom is a "peeping tom," a rapist or a paedophile, and it is unconscionable for any legislator to purposefully place her in such a compromising position."

Strong stuff. Is there any evidence that transgender people are paedophiles or sexual predators?

No, but that's not his point; he's worried that any ill-disposed person could abuse his permission.

Fair enough. The privacy issue doesn't seem entirely unreasonable, either.

Neither, perhaps, is it entirely reasonable. The point about being transgender is that if you're born a man you try to look like a woman. So a biological male who identifies as a female is not going to go into a women's toilet sporting a beard and a beer belly. Looking like your opposite gender is easier for some people than it is for others, but North Carolina can't say how it will police its controversial law. Is it going to insist on some sort of gender test for masculine-looking women or feminine-looking men? That way madness lies. And very expensive lawsuits.

Can you clear up another thing? How do you define transgender?

An excellent question, and one that compounds the state's woes. In North Carolina, only people who have had gender reassignment surgery can have their birth certificates altered. So men who are convinced they are women, to all intents and purposes, who have hormone therapy and dress as women – like Caitlyn Jenner – can't use women's loos, but if they go for the full treatment they can.

Something tells me there's more going on here than just caution about mixed-gender lavatories.

You're right. North Carolina is a conservative state which tried for years to ban same-sex marriage. One of the problems conservatives have with transgender people is that if they marry someone of the "opposite" gender, it's still in their view a same-sex marriage. Peter Sprigg says: "To suggest that the identification of a human being's sex at birth represents merely an 'assignment', as though it were entirely a social construct agreed upon by the child's parents and physician, is absurd. Sex is an objective biological reality... It is simply foolish to treat this as a characteristic that can be changed at will." Many people are very worried about the idea that gender isn't entirely fixed, seeing it as harmful to society and to the individual.

But there can't be too many transgender people around anyway, surely?

No, there aren't. Livescience cites a report from the University of California that says it's around 0.2-0.3 per cent of the US population, or around 700,000 people. A minority of these have undergone surgical gender reassignment.

But that as it may, some people really do feel they're in the wrong body.

Yes, and that's important. There are genuine questions to be asked about what sort of therapy is appropriate for people in this position. However, one thing that ought to be pretty basic is that they shouldn't be stigmatised, demonised or discriminated against. Opponents of the law say this is exactly what's happening. Under its provisions a man who looks, dresses and feels like a woman is being told they have to use a male public lavatory, no matter how humiliating it might be. The message the law conveys is that they're freaks, and critics are outraged at what this says to people who are often very vulnerable and in poor mental health anyway; as many as 41 per cent of US transgender people have attempted suicide, says Livescience.

It's all a bit depressing.

It is. The trouble is that conservative Christians are very exercised about the whole sexual identity thing, and transgender people have been caught in the crossfire. The state has arguably created a huge problem for itself by creating a problem where none existed. Conservative Christians have added to the perception that they are really hateful people by appearing to vilify and demonise people who are often sad and vulnerable. For instance, the president of campaigning law group The Liberty Council, Anita Staver, announced on Twitter she would be taking her gun with her if she needed to use the lavatory at Target: "I'm taking a Glock .45 to the ladies room. It identifies as my bodyguard."

There are legitimate and worrying questions about how America approaches issues of gender. Conservatives might reasonably argue that treating it as entirely optional and normalising 'identities' that don't correspond to biology is storing up a lot of psychological problems for the future. But threatening to shoot people who just need to use the toilet doesn't really advance their case very far.

Are you saying you agree with Donald Trump?

Never thought I'd say this, but yes. Leave it alone, said The Donald. "There have been very few complaints the way it is. People go, they use the bathroom that they feel is appropriate."

After all, transgender people are children of God, too. What does it say about Christianity when they're humiliated and bullied? Come on, America; you can do better than this.

Follow Mark Woods on Twitter: @RevMarkWoods