CS Lewis wrote what he meant by Till We have Faces:

An author doesn't necessarily understand the meaning of his own story
better than anyone else, so I give my account of Till we have Faces simply for
what it is worth. The 'levels' I am conscious of are these:

A work of (supposed) historical imagination. A guess of what it might
have been like in a little barbarous state on the borders of the Hellenistic
world of Greek culture, just beginning to affect it. Hence the change from the
old priest (of a very normal fertility mother-goddess) to Arnom; Stoic
allegorizations of the myths standing to the original cult rather as Modernism
to Christianity (but this is a parallel, not an allegory). Much that you take as
allegory was intended solely as realisitic detail. The wagon men are nomads from
the steppes. The children made mud pies not for symbolic purposes but because
children do. The Pillar Room is simply a room. The Fox is such an educated Greek
slave as you might find at a barbarous courst--and so on.

Psyche is an instance of the anima naturaliter Christiana making the best
of the Pagan religion she is brought up in and thus being guided (but always
'under the cloud', always in terms of her own imaginations or that of her
people) towards the true God. She is in some ways like Christ because every good
man or woman is like Christ. What else could they be like? But of course my
interest is primarily Orual.

Orual is (not a symbol) but an instance, a 'case' of human affection in
its natural condition, true, tender, suffering, but in the long run tyrannically
possessive and ready to turn to hatred when the beloved ceases to be its
possession. What such love particularly cannot stand is to see the beloved
passing into a sphere where it cannot follow. All this I hoped would stand as a
mere story in its own right. But--

Of course I had always in mind its close parallel to what is probably
happening at this moment in at least five families in your home town. Someone
becomes a Christian, or in a family nominally Christian already, does something
like becoming a missionary or entering a religious order. The others suffer a
sense of outrage. What they love is being taken from them. The boy must be mad.
And the conceit of him! Or: is there something in it after all? Let's hope it is
only a phase! If only he had listened to his natural advisers. Oh come back,
come back, be sensible, be the dear son we used to know! Now I, as a Christian,
have a good deal of sympathy with those jealous, suffering, puzzled people (for
they do suffer, and out of their suffering much of the bitterness against
religion arises). I believe the thing is common. There is very nearly a touch of
it in Luke II. 38, 'Son, why hast thou so dealt with us?' And is the reply easy
for a loving heart to bear?

(letter to Clyde Kilby, February 10, 1957; in LL, 273-74).

from http://www.montreat.edu/dking/lewis/TILWEHAV.htm