When is a Religious Belief Delusional?

[Angrboda]

Not if it's taken to be a political construct rather than an inherent or objective fact.  Moreover, even as an inherent or objective fact, it can be derived from the morals of fairness, that all should be treated as equal, regardless of any objective existence of such an equality.

Any notion of fairness already presupposes some measure existential equality. You're arguing in circles.

No, it does not. The notion of fairness creates an imperative to treat identical members consistently. That's a question of identity, not of inherent value. Do we have reason to believe that all humans share the identity of human independent of ideas that we should? Yes, we do. So it's not circular.

Let's step further back. I believe there are moral facts. Are those delusions?

I don't know. Are you saying that the existence of moral facts is similar to the existence of God, something we can impute to exist, but which is otherwise not capable of demonstration? I would debate that because moral facts aren't suggested to exist in the same sense, ontologically, as God is. We accept that numbers exist. Is the existence of numbers a delusion? I would probably have to say that moral facts are currently unexplained. Both moral realism and anti-realistic views on morals provide explanations which are not parallel to the idea of God as a reality. And many non-realist explanations can, in principle, be demonstrated.