Hopefully a foreshadowing of things to come. PETER Costello last night condemned "mushy multiculturalism" and told Muslims who could not tolerate others to leave Australia. The Treasurer said the citizenship pledge of loyalty and respect for law should be a "big flashing warning sign" for those Muslims. Mr Costello departed from economic matters to address Muslim protests following the publication of cartoons depicting the prophet Mohammed. He said those offended "must recognise this does not justify violence against newspapers, or countries that allow newspapers to publish them". His comment reinforced the stand of Prime Minister John Howard, who this week criticised Muslims who were "utterly antagonistic to our society". Mr Costello said Australia was a secular nation and law was set by Parliament under the Constitution. "There are countries that apply religious or sharia law â Saudi Arabia and Iran come to mind," Mr Costello told the Sydney Institute. "If a person wants to live under sharia law these are countries where they might feel at ease. But not Australia." Calling for enforcement of the values pledged in the citizenship oath, Mr Costello recalled a ceremony he had attended this year at which people from 36 countries became Australians. He said a state MP told the audience citizenship did not mean having to give up culture or language or religion or opinions, or love of their native country. "The longer he went on about how important it was not to give up anything to become an Australian the more it seemed to me that, in his view, becoming an Australian didn't seem to mean much at all â other than getting a new passport," he said. He called that view "confused, mushy, misguided multiculturalism" which underestimated those taking out citizenship. "They are conscious that this is not a trivial event. It is a big decision. Becoming a citizen of another country changes their identity," he said. Mr Costello said the citizenship oath tried to capture the essence of what it meant to be an Australian, and the values of loyalty, democratic beliefs, respect for liberties and obeying laws. "Before entering a mosque, visitors are asked to take off their shoes. This is a sign of respect. If you have a strong objection to walking around in your socks, don't enter the mosque. "Before becoming an Australian you will be asked to subscribe to certain values. If you have strong objections to those values, don't come to Australia." Mr Costello said hardline Muslims born here represented "citizens who are apparently so alienated that they do not support what their own country stands for".