When is a Religious Belief Delusional?

[Whateverist]

I suppose at the end of the day we are all influenced by various experiences and sources.  If reading the bible or Aquinas or Confucius helps someone to focus their ideas regarding morality that doesn't do any harm.  But if they conceive themselves to be heeling to divine orders their humanity is diminished and they will become a tool for somebody.

I agree with all this. Whether something is harmful or not has no bearing on whether or not something is true or delusional. And I think you know that from your posts. Others seem to be avoiding the issue.

Just to push you a little further is it delusional to believe the Gospel accounts are historical documents in the same sense as Plutarch's Lives?

I don't know.  History is a hard area for me to think about in these terms.  Confirmation bias is always in play.