Scientology Debate Down Under

Senator Nick Xenophon demanded an investigation of the Church of Scientology. He asserted: "I also believe the activities of this organisation should be scrutinised by parliament because Australian taxpayers are, in effect, supporting Scientology through its tax-exempt status. I say to all Australians: as you fill in your tax return next July or August, ask yourself how you feel knowing that you are paying tax and yet this criminal organisation is not.
"Do you want Australian tax exemptions to be supporting an organisation that coerces its followers into having abortions? Do you want to be supporting an organisation that defrauds, that blackmails, that falsely imprisons? Because, on the balance of evidence provided by victims of Scientology, you probably are."

There are two articles that summarize the issues available at: http://www.theaustralian.com.au/news/nation/police-take-up-scientology-complaints/story-e6frg6nf-1225799494770
and
http://wl.theaustralian.news.com.au/story/0,25197,26378104-5014047,00.html.

I am not a supporter of Scientology, but the debate raises important questions in the modern world. Can, or should, the government define what is a legitimate religious organization? If so, what criteria do they use? If not, can any organization lay claim to the specific rights of a religious group? Should religious groups be granted tax-exempt status? If so, can any religious group be denied such status? Can, or should, the government forbid particular practices of a religion? If so, what standards should be used? If not, would this open the door to an "anything goes" on the religious front?