Yes halt islamic immigration.How do you propose doing that. You do realise Then what do you think would happen to trade with the islamic trade partners - middle east to africa to asia. If it comes to the Saudi Alliance and Australian Alliance and knowing the trustworthiness on the US, who do you really think the US of A will want to maintain? Then comes the reciprocal bans for Australians in Africa - a lot of Australian companies owns mines in Africa. Then the matter of fuel. Then a matter of economic ties with China and Russia - allied to the Islamic nations more than the west.
The reality is the world is tied economically as a deterrent to prevent such illogical manoeuvres. As mentioned before, notice the people on the radical fringe? Most are Aussies. Born and bred in this country, schooled in this country and were actually living an australian way of life. So the immigration was a success before they were exposed to the radicals. Remember, the supposed ISIS order came from overseas not within.
The solution is not as narrow and simple. Otherwise Australian leaders would have already gone down that path.