Instead of punishment this can be viewed as the natural consequence of their own behavior of giving in to the temptation (ego) to seperate from God. This represents a move from Unity (the Garden of Eden) to duality where existence becomes problematic and suffering and mortality begin.
I guess since we are theistically talking about this:
The reason behind the Fall is often described as being hubris, man's search for knowledge and forces that originally were not meant for him to acquire. The Left Hand Path leads to a second birth, a spiritual rebirth as a god/creator. Lucifer shows this direction as the Serpent.
The original Tree of Life did not contain the material world, instead the non-Sephira Daath existed., united by paths with Kether (above), Chokmah, Binah, Geburah and Tiphareth (below). The Fall has corrupted this Tree of Life and shifted the Sephira.
Lucifer-Daath, the original Serpent, represents the divine force of creation that is able to carry out the idea of creation. Lucifer-Daath sinks down to man's level and awakens the power of creation and the sexual energy in man. Thus, man can reach the knowledge which was previously only accessible to God.
Gnostic Gospel: Reality of Rulers (Nag Hammadi)
"It is Samael and his fellow 'rulers' of the Darkness (Eph.6:12), not the true God, who formed Adam's physical body, set him to work in Paradise, "to till and cultivate it" then put him to sleep and fashioned his female partner out of his rib.
It is this God that commanded Adam not to eat of the Tree of Knowledge, which could open his eyes to the Truth. When Adam & Eve, enlightened by the feminine spiritual principle who appeared to her in the form of the Serpent and deified them.
God threw mankind into great distraction and into a life of toil, so that humankind might be occupied with worldly affairs, and might not have the opportunity of being devoted to the Holy Spirit / Higher-Self.
In Reality:
As Jung saw so clearly, the tradition of a Fall from the Garden of Eden' is an archetype. The Original Sin is Man's guilt of being carnivorous and lycanthropic.
We are all descended from males of the carnivorous lycanthropic variety, a mutation evolved under the pressure of hunger caused by the climatic change at the end of the pluvial period, which induced indiscriminate, even cannibalistic predatory aggression, culminating in the rape and sometimes even in the devouring of the females of the original peaceful fruit-eating bon sauvage remaining in the primeval virgin forests.
It was the 'clothes of skin' and the 'aprons of fig-leaves', that produced the nakedness of man, and not the other way round, the urge to cover man's nudity that led to the invention of clothing. It is obvious that neither man nor woman could be 'ashamed' (Gen. ii. 25) or 'afraid because they were naked' (Gen. iii. 10 f.) before they had donned their animal's pelt or hunters' 'apron of leaves', and got so accustomed to wearing it that the uncovering of their defenseless bodies gave them a feeling of cold, fear and the humiliating impression of being again reduced to the primitive fruit-gatherer's state of a helpless 'unarmed animal' exposed to the assault of the better-equipped enemy.
The uncovered body could not have been considered 'indecorous' or 'im-moral'.
The very feeling of sin, the consciousness of having done something 'im-moral', contrary to the mores, customs or habits of the herd, could not be experienced before a part of the herd had wrenched itself free from the inherited behaviour-pattern and radically changed its way of life from that of a frugivorous to that of a carnivorous or omnivorous animal.
- from a lecture delivered at a meeting of the Royal Society of Medicine by ROBERT EISLER First published in 1951 by Routledge and Kegan Paul Limited Broadway House, 68-74 Carter Lane, London, B.C.4
Printed in Great Britain by Butler and Tanner Limited Frome and London