Stephen,
So how did you decide that your experience of God was an experience of an objectively true God?
He liked the feeling.
Really liked it.
Also...
...oh no, sorry. That was it.
The scam he's attempting here by the way is to re-define "philosophical naturalism" to mean, "the natural is all there is or can be" rather than its actual meaning (ie, that the natural is all we can reliably access, test, model and predict pending any evidence to the contrary). Then he labels the rest of us with his own personal definition, and demands that we justify it.
He's also entirely oblivious to the fact that - even if he could ever find someone who
did accept his personal definition - all that would leave him with would be an "anything could be". It would say nothing about the probability of his or any other god, and if he really wanted to use it as a back door to let in his god then he'd have no choice but to let in to any other "just popped into my head-ism" too, leprechauns included. After all, "anything might be" (with which no-one disagrees) just means, well, that
anything might be.