Some time next year, the European court of human rights will decide on the case of a Dutch woman who feels unfairly treated because her country’s highest court has told her she cannot wear a plastic colander on her head for her ID photo.

It may combine Mienke de Wilde’s plea with that of an Austrian former MP, Niko Alm, who proudly wears the offending kitchen utensil on his official documents but now insists his country recognise Pastafarianism – the faith both follow – as a religion.

Watching the pair closely is Mike Arthur, an independent American film-maker whose smart, funny but above all thought-provoking documentary, I, Pastafari, about the world’s fastest-growing faith premieres in the US in October.

All in all, it is shaping up to be quite a big few months for the Church of the Flying Spaghetti Monster, whose believers wear strainers on their heads in homage to their deity, strive to be nice to pretty much everyone, and conclude their prayers with “r’amen” rather than “amen”.

It sounds, of course, like a joke. On one level, it is. But for Arthur, who has spent three years working on his film, and for many Pastafarians who believe their faith embodies some profound – and profoundly important – principles, it is a lot more.

Mienke de Wilde’s ID card photos. Photograph: www.ipastafaridoc.com

“We live,” says Arthur, sitting in an Amsterdam cafe, “in the age of unreason. We no longer value the best idea, but the loudest idea. From Brexit to Trump, we applaud blind faith and are sceptical about overwhelming observable evidence.

“The problem is that rationality is just no match for irrationality. That ship sailed in 2016. People now don’t change their minds, they double down on their irrationality, and using facts, science and reason to contest the unreasonable is simply driving us all further apart. Maybe it’s time to try a different approach.”

A different approach is, undeniably, what Flying Spaghetti Monsterism offers. The church was founded in 2005 by Bobby Henderson, at the time a 25-year-old US physics graduate, as a response to Christian fundamentalists demanding the teaching of creationism in Kansas school science classes. Its name is a portmanteau of pasta and Rastafarianism.

In an open letter, Henderson argued that if intelligent design was to be taught alongside evolution, so should the belief that, with the aid of His Noodly Appendages, an invisible and undetectable Flying Spaghetti Monster created the universe, probably after drinking heavily (thus explaining its many flaws).

Like other religions, the church has a gospel and, rather than commandments, eight “I’d really rather you didn’ts” (two having been lost). These suggest ways to live your life happily without infringing on others’ rights to do the same – a morality based on harmonious co-existence, nonjudgmental conduct “and generally not being a dick”.

Henderson’s basic point, expertly if satirically made, was that since intelligent design was every bit as much of an evidence-based theory as the unshakable belief that the world was created by an omniscient flying monster made of spaghetti, nothing should be taught in science classes bar science.

Mathé Coolen, an archbishop of Pastafarianism, wearing his colander in court in a still from the documentary. Photograph: www.ipastafaridoc.com

But as it has grown – there are now Pastafarians from Poland to New Zealand and Italy to Taiwan, and the church is officially recognised in at least four countries – it has begun posing bigger questions: what actually is a religion? Who gets to decide that? And why should faith – or lack of it – have anything to do with rights?

For Derk Venema, an eloquent Dutch legal expert who has worked with De Wilde, his former student, to develop her arguments for wearing a colander on her driving licence photo, Pastafarianism raises genuine human rights issues – even if (or perhaps because) it is also satirical.

“I started out thinking this was just a big joke,” Venema says. “But the more you look at it, the more you see it is about fundamental principles. The Dutch courts have denied it has any serious message, but it manifestly does: non-violence, tolerance, loving each other – the same principles as many established religions.”

The European court has previously determined that to be recognised as such, a religion must be cogent, coherent, important to its followers, and “serious”. On the latter point, Venema argues that the humour and good fun of Flying Spaghetti Monsterism is simply a more modern, accessible way of getting its message across.

As De Wilde – who after three long years is starting to struggle with wearing a colander every day, but whose determination to take her case to the European court remains undimmed – puts it: “The fact that the church is fun doesn’t mean it isn’t serious in what it stands for.

“I can imagine it all looks very odd if you’re not a believer. But that’s the case with many faiths – people who walk on water or split themselves in three, for example. Personally, I find other religions unbelievable.”

De Wilde reads the Gospel of the Flying Spaghetti Monster. Photograph: www.ipastafaridoc.com

Moreover, argues Venema, even theologians have “never really been able to agree on what constitutes a religion. So should the state really get to decide? For me, if it looks like a religion, with certain customs and traditions; if its followers call it a religion; and if they call themselves believers, that should be it.”

Most importantly, in many societies belief in an established religion comes with certain privileges: from the right to sport religious headwear on your ID photo in the Netherlands, to faith schools in the UK and full-scale tax exemption for US megachurches. “We say, as long as there are special rights for believers, they should apply to all religions,” says Venema.

Alm, a journalist, writer, publisher and former MP, has fought his five-year court battle to get Pastafarianism recognised as a religion in Austria as part of a broader struggle for a true separation of church and state and genuine religious freedom – which, he argues, should include freedom from religion.

“All we ask is a level playing field,” he says. “Total neutrality of the state towards whatever belief I hold. We don’t want anything forbidden, but the law must apply equally to all of us, whatever we believe in and whether we believe nothing at all. Complete freedom of religion. It’s political.”

He readily concedes, however, that Flying Spaghetti Monsterism is a diverse church. “For some, it’s not a political thing at all. In some countries, Pastafarians mainly just want to have fun and eat pasta.”

Bruder Spaghettus, a leading German Pastafarian, by a ‘noodle mass’ sign in Templin outside Berlin Photograph: www.ipastafaridoc.com

Arthur, whose film follows Venema and Alm through their court battles and also features Bruder Spaghettus, the luxuriantly bearded leader of the Kirche des Fliegenden Spaghettimonster in Germany, says Pastafarianism is like other religions, with a supernatural deity, a prophet, and lessons of morality in holy scriptures.

“Unlike other religions, it’s left out hate, bigotry, violence and dogma – its only dogma is that there is no dogma. But by challenging innocuous privileges like the right to wear religious headgear on an ID photo, it makes us think about others, like the right not to vaccinate your children, say, or to use tax-free income to buy private jets so you can fly round preaching science is a conspiracy.”

So Pastafarians, says Arthur, whose film premieres at the Nashville film festival in the first weekend of October, “are actually saying, ‘Look, if no one’s going to talk to each other like adults any more, let’s try something else.’

“By putting their own beliefs on display, in a fun way, they make us think more deeply about ours. And in a time of flat-earthers, anti-vaxxers, fake news and alternative facts, they may just be the saviour we’ve been waiting for. R’Amen.”