Even in Melbourne, where Italian and Greek migrants transformed the city in the post-war generation, more residents now speak Chinese or Indian languages at home than Greek or Italian - and almost one in five Melbourne residents is of Asian ancestry.

Diversity has won the battle for Australia. It has become a country where - for better or for worse - more and more people are abandoning the old cultural norms. More parents and live-in partners are unmarried. Only 61 per cent of Australians now call themselves Christians, down from 68 per cent a decade ago.

For the first time, most Australians aged 25 to 34 are no longer Christians. Just 49 per cent identified with any Christian denomination - almost half of them Catholics - while 10 per cent declared themselves for Buddhism, Hinduism, Islam or Judaism, 3 per cent professed other beliefs, 29 per cent said they had no religion and 9 per cent gave no answer.

Catholicism is resisting the tide, but the main Protestant denominations are seeing their numbers erode away. In 1981, 26 per cent of Australians said they were Anglicans; in 2011, just 17 per cent were. The Catholics have lost some ground among the young, yet in sharp contrast to the Anglicans' fate, 25 per cent of Australians still call themselves Catholics.

Marriage too is losing ground. The census found fewer than half of Australians over the age of 15 are married. The Prime Minister and the First Bloke were among almost 1.5 million Australians living in a de facto relationship - almost 10 per cent of the adult population. More de facto relationships now include children. In a decade, the number of children living with de facto families has swelled almost 50 per cent to 526,000: one in 10 children.