Previously, a charity could be formed under the head of "Advancement of Religion" and that was taken as a charitable purpose. The 2006 Act introduced a new requirement that the charity must show that it is for the public benefit. It was always that case that a particular religion could be deemed not to be a charity but the legal position now is that no religion is deemed to be a charity ipso facto, there must be a demonstration of something else called "public benefit".
Public benefit is not defined in the Act and it has been left for the Charities Commission to consult on the matter. On this, see my previous post Charities Act and the secularist agenda which offers some analysis of the consultation process.
Andrea Minichiello Williams, barrister and public policy officer at the LCF said:
It is of concern that the Charity Commission has said it will interpret 'public benefit' in the light of 'modern conditions'. What this could mean for Christian charities that exist for evangelism or which promote traditional Christian teaching on family and life issues is unknown."Here is a link to the LCF's full response to the consultation (pdf)