Kylie Sturgess loves science fiction - so much that at the last census, the radio tutor marked "Jedi" in the religion section. Her husband, who has attended several sci-fi conventions with her, did the same.
"We thought: why not put down Jedi?" Ms Sturgess said.
"It seemed hilarious.
"We didn't really reflect on it."
Ms Sturgess and her husband were far from alone.
In the 2011 census 64,390 Australians marked Jedi as their religion, up from 58,053 in 2006. This put the number of Jedi in Australia just behind Sikhs and above Seventh Day Adventists.
The Jedi phenomenon began in 2001 when an email campaign mistakenly claimed the government would have to recognise it as an official religion if 8000 people selected it in the census.
Now Ms Sturgess, president of the Atheist Foundation of Australia, is leading a campaign for people not to treat the census as a joke.
This is because if people fill in the "other" box in the religion section of the census with an answer such as Jedi they are counted as "not defined" rather than "no religion".
Ms Sturgess said this skews the census results by making Australia appear more religious than it is.
"People shouldn't waste their answer," she said.
"Answering the religion question thoughtfully and honestly matters because it benefits all Australians when decisions on how to spend taxpayer dollars are made on sound data that accurately reflects modern-day Australia."
Posters promoting the campaign to tick the "no religion" box say: "If old religious men in robes do not represent you don't mask yourself as 'Jedi'."
Avid Star Wars fan Chris Brennan, from Melbourne, said: "Some people put down Jedi as a snub to the government, saying, 'You can't tell me what to do.'
"But others put it down as a serious commitment."
Mr Brennan said there are "many genuine followers of the Jedi way and they're not all nut jobs and ferals".
He said the Jedi belief system includes views such as "all life is sacred", "be kind to others" and "protect the innocent and the weak". The phrase "no religion" does not necessarily sum up many people's views of faith even if they don't follow an organised religion, he said.
This year's census, to be held on Tuesday August 9, will be the first where "no religion" sits at the top of ten possible responses rather than at the bottom.
At the 2011 census, 22 per cent of Australians chose "no religion" with Catholics on 25 per cent and Anglicans on 18 per cent.
Ms Sturgess said people can still feel spiritual and lead moral lives without identifying as religious.
Separate email campaigns by anti-Islam groups are urging Australians to select a Christian religion on the census, even if they are not practising, to stop Australia becoming seen as a "Muslim nation".
In the last census 2.2 per cent of Australians identified as Muslim.
