Ooops ! that should read are the #1 loophole for Islam not to gain ground.

//Every culture should have their own nation.//

Great, where are we going to send the bogans? I vote for founding the new nation of Boganistan in what is currently known as The Little Sandy Desert', a long way away from me.

Although.... this is going to get complicated. For example, I'm sure we can all agree that religion is a very big part of culture: if two people don't share the same faith, how they can be said to share the same culture? So realistically, the only way to do what you're proposing fairly will be to start divvying up Australia along sectarian lines: a bit for the Catholics, and one for the Anglicans, another for the Jews, a bit very far away for the happy-clappers so we don't have to listen to their shite Christian rock, etc etc.

Now, I'm not sure how I'd feel about becoming a citizen of a new country. Who knows, it might not be that bad. But I can see some problems with this idea. Take defence, for example: once we get rid of Australia the ADF goes to; instead of one big, strong nation you wind up with a multitude of micro-nations that could be conquered by a pack of cub scouts and their terrier mascot. When viewed from that angle, your brilliant idea to give each culture their own nation sounds like a plan to give each culture their own nation, with that nation being 'China'. No thanks.

And then there's transport. Since all these little nations will be sitting on the land mass we call Australia, there are going to be a lot of shared land borders, and people will want to move about. I'd have to live in Pantheist Oz, but my parents would be in Catholic Oz and obviously I'd want to visit them. If I took a job with some religious outfit, I'd have to travel internationally just to go to work. Imagine the chaos that could ensure if all these different nations decide to use different rail gauges...

It seems to me that in order to deal with practical matters like these, our hypothetical new nations might have to set aside their differences, focus on their commonalities and band together as some sort of 'Federation' or 'Commonwealth'...

Wait, hang on a second.

'One thing of great comfort for me as an atheists is the fastest growing "religion" in Australia is, no religion at all,'

yep the suppressors of truth and dumming down of people is happening. Some god deniers are stupid enough to think God needs numbers. No wonder the god deniers hate Israel so much.

While we are tinkering around the edges, thinking that the political elites give a stuff what we think about race or culture, the globalist corporations, the UN and the EU, are busily working on removing borders and national sovereignty. The crap Left media (there's not much else these days) is supporting them, either directly or by not broadcasting what's going on. Most people simply don't know what is going on; they just believe what the media tells them, and feel qualified to rubbish people who do know what's going on.

Some god deniers are stupid enough to think God needs numbers. No wonder the god deniers hate Israel so much.
runner,
You're overlooking the loophole there. Whenever a Census is taken the majority is what gets the nod for whatever its agenda may be. So, If there are suddenly 51% of residents in Australia identifying as Muslim then Australia will be deemed a Muslim Country. We really need more than 51% atheists of decent character to keep the next looming dark Age at bay.