When is a Religious Belief Delusional?

[Angrboda]

As a social species, we have evolved mechanisms for identifying those like us.  We identify the commonalities and ignore the differences because we evolved to do so.  When is the last time you experienced sexual attraction for a duck?

Fuck a duck. :-) Recognizing a potential mate is vastly different from recognizing him or her as an equal.

No, it requires recognizing them as the same as you and then applying an imperative of fairness. That was the point, and it still holds. The point being that recognition of human sameness doesn't rest upon arbitrary grounds.

We owe as much of our cultural heritage to the Greeks and others in the region,...

Yes, Hellenistic ideas were imported into the Christian tradition. Yes, other cultures independently developed similar values. One could conceivably argue that ideas of universal equality are  latent in some Stoic texts, but the fact remains that these values never came to fruition in the same way they did in Christianity. That those latent values were not immediately recognized by the early church does not refute that fact that those values are in scripture and were eventually brought forth.The idea of “all men are created equal, that they are endowed by their Creator with certain unalienable rights” was a revolutionary and historically unique formulation born out of the Judeo-Christian tradition.

Be all that as it may, this thread is about whether or not religious beliefs are categorically delusional. Having an alternate secular account of the source of moral sentiments or whether Western moral values come out of Christianity is not germane to the topic of the thread. Is it delusional to attribute those values to a transcendent source, such as believed by as diverse thinkers as Plato, Emerson, and Kant?

The point is their ubiquity argues that there is a biological basis which transcends cultural differences, something you were arguing against with this "we got it from Judeo-Christianity" crap. Having a secular account provides a rational basis for belief in those things. The question was is it delusional to believe in those things. If they have a rational foundation, then no it is not. Is it delusional to believe in Plato's forms? As noted below, I don't think that falls into the same category, so it would be a moot point either way.

… my question about the disanalogy between beliefs like the existence of human equality and that of the existence of God.  That's still valid in lieu of an objection.

If you don’t like the analogy then use mathematical realism as a better one. I would like to see you argue that considering mathematical objects real is delusional.

Mathematical realism fares no better as it is well recognized that the ontology of numbers and morals is significantly unlike the ontology of existents like this desk, or a supposed god, thus unless you can reconcile those differences, your argument to analogy fails. Even if we recognized that belief in numbers was not in some sense rationally founded, that it was some form of error, we would not conclude that it is the same sort of error as believing in the existence of an immaterial being which can act and interact with the real world.