The whole point is not to "presume naturalism". You are presenting the case for non-naturalism; the onus is on you to demonstrate the evidence for even supposing the actuality of such a thing.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'