Aboriginal religion, like many other religions, is characterised by having a god or gods who created people and the surrounding environment during a particular creation period at the beginning of time. Aboriginal people are very religious and spiritual, but rather than praying to a single god they cannot see, each group generally believes in a number of different deities, whose image is often depicted in some tangible, recognisable form. This form may be that of a particular landscape feature, an image in a rock art shelter, or in a plant or animal form.
As opposed to Christians and believers of many other religions who go to a church or a mosque to pray, Aboriginal People express their beliefs in spiritual rituals. In the old days when they all lived traditional life, they went to their sacred mountain or any other natural feature that was believed to be their creator (different tribes had different objects), and they performed spiritual ceremonies.
Similar to other religions, there was a time in Aboriginal belief when things were created. This “Creation Period” was the time when the Ancestral Beings created landforms, such as certain animals digging, creating lagoons or pushing up mountain ranges, or the first animals or plants being made.
Many Aboriginal People have also changed their beliefs since European invasion. Early missionaries forced them to learn the Bible, so there are some Aboriginal People who are Christians. There are even some Muslims, even though they are much fewer than Christians.
But most Aboriginal People haven't given up their original beliefs, they still believe in their own creation story, although probably in a new perspective. They now know that they have been in Australia for 60,000 years, so the Dreamtime has now changed from "the beginning of the time" to 60,000 years ago.
God is either necessary or unnecessary.
God is not unnecessary, therefore God must be necessary.
Therefore, God exists.