"I'm not about to advertise it for fear of it having a lot of new followers on a fairly unfair basis," he said at the weekend, after announcing other loopholes would be tightened to stop parents claiming childcare and family benefits if they refused to vaccinate their children. An online guide produced by Mr Morrison's own department clearly states that the exempt organisation is Church of Christ, Scientist - more generally known as the Christian Scientists. This information is also available on the government's ComLaw website, where an explanatory statement about exemption from immunisation requirements states that "children of practising members of the Church of Christ, Scientist are exempt". It explains that this "clearly advances" freedom of religion for Christian Scientists as "their religious beliefs mean they may be unwilling to access western medicine". This is under a determination made by Labor's Jenny Macklin in 2012, when she was families minister. But Christian Scientists have long been seen as a special case, with the Australian Democrats arguing in Federal Parliament as far back as 1998 that the group should be exempt from penalties for not vaccinating their children.

On Tuesday, Christian Science Australia spokeswoman Kay Stroud told Fairfax Media that the church was in fact "very neutral on the subject of vaccination" and did not make a suggestion to followers either way. Ms Stroud also said the church would be able to determine if people were joining it simply to get out of vaccinating their children. "We're not silly," she said. In order to claim religious exemption, parents need to provide the government with a letter from an official of the church, declaring that the parent is a practising member. A spokesman for Mr Morrison said information about religious exemptions "has been available on the department's website".

He said the Social Services Minister's previous comments on not stating who the church group was "related to not promoting this exemption". "The exemption for this religious body was not authorised by the current government," he added. "There is no evidence to suggest that this exemption has been abused or is the reason for the strong increase in conscientious objections to immunisation during the past 10 years. "The government will monitor this arrangement closely and reserves the right to cancel this registration if the integrity of the scheme is believed to be compromised." Mr Morrison has said the religious exemption related to a " very, very, very small proportion of people – it'd be lucky to be in the thousands, if that".

Christian Scientists do not come up as an individual category in the 2011 Census, but are included in the general "other Christian" group, which makes up about 4.5 per cent of the population and includes groups such as the Quakers. On Sunday, Prime Minister Tony Abbott and Mr Morrison announced the new measures to boost vaccination, noting that the rate of objection to immunisation had risen from under one per cent to about 2 per cent over the past decade. Under the new policy, families with children who are not immunised will only be able to keep receiving childcare payments and Family Tax Benefit Part A if they have religious or medical grounds for objecting. CHRISTIAN SCIENCE What is it?

Christian Science is based on the Bible and explained in writings by 19th century US founder Mary Baker Eddy. Among other things, it believes there is a link between prayer and health - as well as other issues such as global issues and employment. The religion states it is up to each Christian Science follower to "choose" what health care they want. But many "decide to pray first about every challenge ... and find it effective". It is not Scientology. Who is involved? The Mother Church is in Boston but there are Christian Science churches around the world, including Australia.

Exact numbers of Australian followers are difficult to pin down but, when asked who the religious exemption would apply to, Scott Morrison has said it would be "lucky to be in the thousands". Follow us on Twitter Like us on Facebook