Why are atheists flocking to join Iceland's fastest-growing religion?

Zuism is one of Iceland's newest official religions, having been recognised in 2013 - but it's been picking up hundreds of new followers in recent weeks, including many atheists.

The reason lies in Iceland's tax system. At present, citizens are required to contribute a congregation tax, known as sóknargjöld, to a religious organisation of their choice - or, if they're not religious, the payment instead goes to the state.

The modern incarnation of Zuism, based on Ancient Sumerian texts, plans to give the cash it receives through congregation tax back to its members. It's also calling on the Icelandic government to cease collating information on citizens' religious beliefs.

The Zuist church has some links with the pro-free speech, anti-authoritarian Pirate Party. Halldór Auðar Svansson, a Reykjavík city councilman for the party, has spoken out in support of the religion, praisining its efforts in “hacking the system,” while Pirate Party founder Birgitta Jónsdóttir is thought to be a Zuist.

The church claims to have about 3,000 members, meaning they now outnumber Muslims by about three-to-one in Iceland's population of 323,000.

Tax authorities have cautioned that, if the Zuist church refund congregation tax (also known as parish fees) to its members, the payments will be subject to income tax.

The church's website says: "The religious organization of Zuism is a platform for its members to practise a religion of the ancient Sumerian people. Zuists fully support freedom of religion, and from religion, for everyone. The organization’s primary objective is that the government repeal any law that grants religious organizations privilege, financial or otherwise, above other organizations. Furthermore Zuists demand that the government’s registry of its citizens’ religion will be abolished."

"The organization redistributes the government’s annual financial support equally to all members of the congregation. The organization’s financial matters are handled by an accountant firm, and general administrative matters are handled by a lawyer. Neither the administrative board nor other members will have access to the organizations financial matters."

"The religious organization of Zuism will cease to exist when its objectives have been met."

Around 80% of Icelanders are members of the Lutheran State Church. 5% are registered in other Christian denominations, and almost 5% Ásatrú, the traditional Norse religion.

Recent polls have indictated that support is mounting in Iceland for separation of church and state. In a Gallup survey published this autumn, more than 55 per cent of respondents wanted the ties to be cut, up about five per cent on the previous year.