Those from one or more generations back who have assimilated in a sharing way and who have shown subsequent respect for their hosts are welcome.
Those who come here with an arrogance and anger and expectation for their hosts to adjust to and bend over backwards to their ways need to be shown the door for a free one-way trip back from where they came from.
I reckon a very simple litmus test can demonstrate the first stage of respect - do immigrants proudly sing the Australian anthem? Those who come up with some sort of excuse should immediately be excused from our fair shores! Merry Christmas, Happy Ramadam or whatever - good riddance.