Having comes across the use of the abject as a conceptual tool to think through political theology and pacifism I did a little digging and came across Julie Kristeva’s Powers of Horror: An Essay on Abjection (link to full pdf); a text cited as forming some of the theoretical basis for the concept’s later development.  The opening paragraph is worthy of a slow read,

There looms, within abjection, one of those violent, dark revolts
of being, directed against a threat that seems to emanate
from an exorbitant outside or inside, ejected beyond the scope
of the possible, the tolerable, the thinkable. It lies there, quite
close, but it cannot be assimilated. It beseeches, worries, and
fascinates desire, which, nevertheless, does not let itself be seduced.
Apprehensive, desire turns aside; sickened, it rejects. A
certainty protects it from the shameful—a certainty of which
it is proud holds on to it. But simultaneously, just the same,
that impetus, that spasm, that leap is drawn toward an elsewhere
as tempting as it is condemned. Unflaggingly, like an inescapable
boomerang, a vortex of summons and repulsion places the
one haunted by it literally beside himself.

And the concluding the opening section,

A massive and sudden emergence of uncanniness, which, familiar as it
might have been in an opaque and forgotten life, now harries
me as radically separate, loathsome. Not me. Not that. But not
nothing, either. A “something” that I do not recognize as a
thing. A weight of meaninglessness, about which there is nothing
insignificant, and which crushes me. On the edge of nonexistence
and hallucination, of a reality that, if I acknowledge
it, annihilates me. There, abject and abjection are my safeguards.
The primers of my culture.

Kristeva in her work on abjection attempts to hover over a fundamental human experience; perhaps the fundamental human experience which is the inability to acknowledge or face our impotence in subsuming life within the bounds of our meaning.  To acknowledge that there is ‘something’ that I cannot recognize as a ‘thing’.

This is the literal shit of human life that I cannot rid myself of so I must always cleanse myself.

This is the desire for mother/father that is at once good and evil (or neither or both).

This is the inherent decay of death within food that is needed for life.

This is the eternal coding of a divine people who will not be assimilated.

These are seemingly universal realities which we cannot live with or live without.  These experiences raise fundamental questions of boundary.  Inside/Outside; Self/Other.  I came from my mother but I cannot return there.  Shit comes out one end but I would vomit trying to put it in another.  I desire to relate intimately but I cannot maintain the space between us I only vacillate between control and abandonment.  What cannot be assimilated as One or faced directly in opposition forms the abject.  A live body can be loved or fought but a dead body . . .

Kristeva traces the expression of abjection primarily in the Judeo-Christian stream orienting herself in Freud and then looking at taboo and ritual in Mosiac law and then the internalization of abjection in Christianity and with it the formation of ‘sin’.

Kristeva then spends several chapters exploring the content of French novelist Louis-Ferdinand Céline.  Celine is a writer of the abject as he continual hovers over the points of life where boundaries break down and where the abject is named and gagged over in fear and attraction (the Jew, the mother).  In his writing Celine attempts to push back the coding of the word to arrive at expressed emotion and with the allowance and facing and expressing of horror.  There is an attempt to explore expression that eludes or throws off the over-structuring and binding of the symbolic.  Kristeva offers this description,

With Celine we are elsewhere. As in apocalyptic or even
prophetic utterances, he speaks out on horror. But while the
former can be withstood because of a distance that allows for
judging, lamenting, condemning, Celine—who speaks from
within—has no threats to utter, no morality to defend. In the
name of what would he do it? So his laughter bursts out, facing abjection, and always originating at the same source, of which Freud had caught a glimpse: the gushing forth of the unconscious, the repressed, suppressed pleasure, be it sex or death. And yet, if there is a gushing forth, it is neither jovial, nor trustful, nor sublime, nor enraptured by preexisting harmony. It is bare, anguished, and as fascinated as it is frightened.

And then further,

A laughing apocalypse is an apocalypse without god. Black
mysticism of transcendental collapse. The resulting scription
is perhaps the ultimate form of a secular attitude without morality,
without judgment, without hope. Neither Celine, who
is such a writer, nor the catastrophic exclamation that constitutes
his style, can find outside support to maintain themselves.
Their only sustenance lies in the beauty of a gesture that, here,
on the page, compels language to come nearest to the human
enigma, to the place where it kills, thinks, and experiences
jouissance all at the same time. A language of abjection of which
the writer is both subject and victim, witness and topple. Toppling
into what? Into nothing more than the effervescence of
passion and language we call style, where any ideology, thesis,
interpretation, mania, collectivity, threat, or hope become
drowned. A brilliant and dangerous beauty, fragile obverse of
a radical nihilism that can disappear only in “those bubbling
depths that cancel our existence” (R, 261). Music, rhythm,
rigadoon, without end, for no reason.

With Celine we reach a sort of climax in which our abjection has moved from external taboo and internal sin to the practice of literature as able to evoke the fascination, fear and power of horror.  In her conclusion Kristeva then asks, And yet, in these times of dreary crisis, what is the point of emphasizing the horror of being?  Here are excerpts of her response,

For abjection, when all is said and done, is the other facet of religious,
moral, and ideological codes on which rest the sleep of individuals
and the breathing spells of societies. Such codes are
abjection’s purification and repression. But the return of their
repressed make up our “apocalypse,” and that is why we cannot
escape the dramatic convulsions of religious crises.

Kristeva then turns to the (psycho)analyst in conclusion,

And yet, it would perhaps be possible for an analyst (if he could manage to stay in the only place that is his, the void, that is, the unthinkable
of metaphysics) to begin hearing, actually to listen to himself
build up a discourse around the braided horror and fascination
that bespeaks the incompleteness of the speaking being but,
because it is heard as a narcissistic crisis on the outskirts of the
feminine, shows up with a comic gleam the religious and political
pretensions that attempt to give meaning to the human
adventure. For, facing abjection, meaning has only a scored,
rejected, ab-jected meaning—a comical one. “Divine,” “human,”
or “for some other time,” the comedy or the enchantment can
be realized, on the whole, only by reckoning with the impossible
for later or never, but set and maintained right here.Fastened to meaning like Raymond Roussel’s parrot to its chain, the analyst, since he interprets, is probably among the rare contemporary witnesses to our dancing on a volcano. If he draws perverse jouissance from it, fine; provided that, in his or her capacity as a man or woman without qualities, he allow the most deeply buried logic of our anguish and hatred to burst out. Would he then be capable of X-raying horror without making capital out of its power? Of displaying the abject without confusing himself for it?

Probably not. Because of knowing it, however, with a
knowledge undermined by forgetfulness and laughter, an abject
knowledge, he is, she is preparing to go through the first great
demystification of Power (religious, moral, political, and verbal)
that mankind has ever witnessed; and it is necessarily taking
place within that fulfillment of religion as sacred horror, which
is Judeo-Christian monotheism. In the meantime, let others
continue their long march toward idols and truths of all kinds,
buttressed with the necessarily righteous faith for wars to come,
wars that will necessarily be holy.Is it the quiet shore of contemplation that I set aside for myself, as I lay bare, under the cunning, orderly surface of
civilizations, the nurturing horror that they attend to pushing
aside by purifying, systematizing, and thinking; the horror that
they seize on in order to build themselves up and function? I
rather conceive it as a work of disappointment, of frustration,
and hollowing—probably the only counterweight to abjection.
While everything else—its archeology and its exhaustion—is
only literature: the sublime point at which the abject collapses
in a burst of beauty that overwhelms us—and “that cancels our
existence” (Celine).