The idea here is that Tolkien and Lewis believed (not just accepted because it
worked for them, but actually believed because they thought they had good
reason to) that the Fall of Man was the truth behind what it is to be human,
and not merely one particular myth. This would not reflect poorly on
prehistoric peoples who, like brilliant scientists trying to come up with a
theory of aether, laboured under the disadvantage of having less information.
Those who do not agree with this premise should probably reject Tolkien and
Lewis' statement in its strongest sense, and should be able to do so without
getting angry. However, they can still mine the statement for more
general meanings, as squire has done.
Sorry for sticking my nose in. I'll go see if I can't post something on
topic
now...