Björn Oback is a Pastafarian, a member of a little known but recognised religion, who received New Zealand citizenship on Friday wearing his customary headgear: a colander.

The first Pastafarian has sworn an oath of allegiance to New Zealand on the pasta-worshipping religion's new holy book.

Björn Oback had the customary blue colander strapped to his head, and "Map of Treasures" in his hand at a citizenship ceremony held at Hamilton Gardens on Friday.

A member of the Church of the Flying Spaghetti Monster, he is the first to swear an oath of affirmation on the church's official holy text - the first edition printed this week for the occasion.

MARK TAYLOR/STUFF Pastafarian Bjorn Oback at the citizenship ceremony in Hamilton Gardens on Friday.

It was an exciting milestone for both the German-born biologist and the church, which plans to become a greater presence in New Zealand life.

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Pastafarianism was founded in the United States by Oregon man Bobby Henderson in 2005 as a response to Christian fundamentalists who were advocating the teaching of creationism in schools.

MARK TAYLOR/STUFF Bjorn Oback receivies his citizenship certificate from Hamilton Mayor Andrew King.

Adherents worship a pasta god called the Flying Spaghetti Monster, wear colanders or pirate garb, and reject "crazy nonsense" while enjoying life, being nice to all sentient beings and feasting on pasta.

While the intention was at first to ridicule fundamentalists of any stripe, any good joke has a serious element, Oback said. He signed up as a virtual member in the first year.

The tall German, who has lived in New Zealand since 2000, elicited a surprised smile from Mayor Andrew King and a quiet giggle from the crowd when he stood to collect his citizenship certificate.

ROSS GIBLIN/STUFF Top Ramen Karen Martyn said the New Zealand Church of the Flying Spaghetti Monster was the first to develop a holy text and would next register as a charity.

Afterward, Hamilton city councillors Paula Southgate and Siggi Henry - the latter also familiar with wearing metal (or tinfoil) headwear to official events - required an explanation for the colander.

"It's Friday, the international Pastafarian day when we celebrate pasta," he said in response.

Oback wasn't the only person demonstrating his faith in the crowd of 127 new citizens from 28 countries, but he insisted the colander wasn't to make fun of others.

"The idea is tolerance about everything, really, it might come across as being a mockery, but it really isn't.

While Oback is a practising Pastafarian, it's more of a lifestyle than religion for his family. His teenage daughter, Maia, said she would "probably" wear a colander when applying for her drivers licence in the future.

The Church of the Flying Spaghetti Monster was officially recognised by the government when it was approved to conduct marriages in 2015, and the country is something of a mecca for Pastafarians.

Top Ramen and Ministeroni Karen Martyn, the church's figurehead, is a registered marriage celebrant who conducted the world's first Pastafarian wedding in 2016.

She said the New Zealand church was the first to develop a holy text to list the religion's principles, called "treasures".

Treasures include: being a nice person, not cutting off body parts or wearing certain clothes, taking care of the environment and supporting euthanasia.

"We want people to do things because it's the nice thing and the right thing to do, not because they have fear of burning in hell in some afterlife.

"Our church is very strongly supportive of anything that improves the well-being of sentient beings."

As registration is not required for the virtual church, Martyn said it was otherwise impossible to know how many adherents the religion had.

"It's not the numbers, it's the niceness. We've got some really nice people and the only God without genitals."

And while they're not actively looking to convert new members - Pastafarians don't like people who push their opinions or imaginary beliefs on others - there are plans in the works for an expansion.

The Church of the Flying Spaghetti Monster will soon be registering as a religious charitable trust.

"Churches are tax-free in New Zealand and we're hoping to draw attention to that so we can get a law change. We would like to see all churches taxed the same as any other organisation or business."