The only reason why these religions have grown in Australia is because of migration. They too will decline when the population of migrants children get educated.

I suppose people think they have to belong to something. Otherwise, I am not impressed.

American Christians are in decline and so is US lifespan. Where the average lifespan around the world has increased a great deal and religion has increased. I don't have an scientific explanation for this, other than nationalism is not socially bringing diversify people together and religion is. People relationships are more important than food. Nature is my religion, and the arts has been my center for relationships. Perhaps each individual must find their own tribe as humans are very social creatures, like dogs.