Completely and utterly false. According to the 2006 census around 69.5 % belong to a religion. In fact, Australia has been very religious in it's past. When more than 2/3 of your citizens are religious, I think that qualifies as being a religious country.
The graph is based on the link below
http://www.abs.gov.au/ausstats/abs@...636F496B2B943F12CA2573D200109DA9?opendocument
Um... having a religious affiliation does not mean you're particularly religious. You have people who identify as Catholic or Anglican but pay lip-service to church and so on.