I have no idea how any of this is relevant to the questions posed to Josh. For the record I believe all the things you say are true. And do I really need to know why he believes what he does? Depends on what you mean by need. I will certainly be able to live without knowing it, and asking him to expand upon it as a means of personal attack.
Asking someone to rationally justify or otherwise explain the basis of their beliefs is not a personal attack or somehow to impugn their character. Particularly when he has claimed his beliefs are not an “aberrant imagination”. The act of stating that in a public discussion board seems to me almost designed to invite further scrutiny. Why else state it? I believe all the theists who post here sincerely do believe.
Though I can’t help but suspect the unwillingness to just explain what the evidence is right out the gate is because he somehow recognizes the evidence is weak, and that he doesn’t really know he’s been contacted by God. He’s probably just interpreted a number of occurrences in his life as having been somehow orchestrated or ordained to occur by divine will. Some people were bad to each other, then stopped and became friends. Or someone in a terrible physical or mental state became well, or someone survived a car crash. These are real-world events given an interpretation of religious significance.
I’d be very surprised to be proven wrong here. Religious people interpret real-world events through the glasses of their beliefs, and then believe the events themselves are evidence for their interpretations.