Sly and.....

Only this, and nothing more....

I buried the lede in that prior post.  The salient point got passed over by yours truly in the rush to define "mystery."  It's here, in the definition (working definition, for the quoted passage) of "religion":

What is a religion? Religion presumes access to the responsibility of a free self. It thus implies breaking with this type of secrecy (for it is not of course the only one), that associated with sacred mystery and with what Patocka regularly calls the demonic. 

So religion is, as Derrida says elsewhere in the same essay, responsibility; or it is nothing at all.

True, we can imagine the classic religious figure as Elmer Gantry, a figure who denies all responsibility yet seeks to profit from what religious fervor can provide.  In the same way we can imagine the mad scientist, the seeker after knowledge who takes no responsibility for the consequences of his discoveries.  Faust without the comeuppance; or the morality, for that matter.   But it's rather unfair to think either figure is typical of religion or science.

To presume religion starts with the question "What makes the rain fall?" and, having no answer, discerns a deity and a doctrine and an organization, is naive beyond measure; not to mention as ignorant as those who deny the conclusions of climate science, and for pretty much the same reasons. If we start with the idea that "Religion presumes access to the responsibility of a free self," we taken in quite a bit more than a caricature of fundamentalist Christianity.  And the limitation to Christianity is something else Derrida mentions:

Under what conditions can one speak of a religion, in the proper sense of the term, if such a thing exists? Under what conditions can we speak of a history of religion, and first and foremost of the Christian religion? In noting that Patocka refers only to the example of his own religion I do not seek to denounce an omission or establish the guilt of a failure to develop a comparative analysis. On the contrary, it seems necessary to reinforce the coherence of a way of thinking that takes into account the event of Christian mystery as an absolute singularity, a religion par excellence and an irreducible condition for a joint history of the subject, responsibility, and Europe. That is so even if, here and there, the expression "history of religions" appears in the plural, and even if one can only infer from this plural a reference to Judaic, Islamic, and Christian religions alone, those known as religions of the Book.

Because certainly, those are the only three religions in human history; right?

These things that pass for knowledge I don't understand.  But we are much better off considering religion as posing Tolstoy's question:  "How should we then live?", than posing the question:  "What makes the rain fall?"  Which brings me back to my point, only with the other prong of my argument.

Science can answer the latter question; but it can't do anything about it.  Funnily enough, neither can religion.  Maybe they have that much in common.