Like I pointed out in my previous post, it is the symbolism that makes the story of the Coorma avatar compelling to read. Of course you may not agree with the message passed on by the story, but that is your problem.
The most comprehensive symbolism of this story was found here, and I shall unabashedly use its contents in this post.
The story states that to obtain the Amrita, the ocean of milk has to be churned. Three symbolisms already in the first line. Amrita, the nectar of immortality, is the final enlightenment achieved by a practising student. It is the true self. The ocean of milk is the pure (white as milk) consciousness that is present within us, which is the complete truth, and is not contaminated by any other. The true self thus resides in the ocean of pure consciousness (#). And the act of churning is the churning that goes on within our minds as we come to terms with the reality. Since the true notion of reality is a huge change of paradigm from the world we think is real, the mind cannot come to terms with it immediately, and the process of this acceptance is the churning. It is unavoidable and necessary. The process of churning itself has a simpler meaning. The story states it as a pull between the Devas and asuras alternately, while it really does mean the pull of the good and the bad which keeps alternating, which is really what leads to the confusion. But like I said, its necessary to achieve progress, it makes you step back and analyze the situation more calmly.
According to the yogic school of thought, the kundalini energy flows up the spinal column, and one must learn to harness this energy for spiritual progress. The Mandara mountain represents the spinal column, and Vasuki, the king of serpants, represents the kundalini, or serpant like energy. As for the first act of asking the Devas to hold the tail of Vasuki, we saw how it was actually a blessing in disguise. The symbolism here is that at times we must be humble enough to perform tasks that seem to be beneath our dignity. It may not be attractive, but it certainly is more beneficial than doing the likeable thing over the long run. Long term benefits over short term gains.
As soon as the churning begins, the mountain sinks beneath the water surface, which is indicative of how any attempt at spiritual progress will falter without a firm foundation. Vishnu incarnating as a tortoise represents the vital breath that provides the foundation for spiritual progress. The Halahala poison that first emerges from the sea is the pain of the paradigm shift, the pain of severe self-introspection. The student certainly is not mature enough to deal with it. Shiva, the greatest yogi known to mankind, is the guru who helps the student in such matters. His swallowing of the poison is indicative of the guru's efforts at placating the student by making the emotional disturbances go away, not permanantly, but atleast upto a point where the student matures enough to handle them. This is why the poison is stuck in Shiva's throat, the part of the body where speech emanates from.
After Halahala, the Goddess of intoxication comes out. This is the intoxication of passing through the first step. If you cannot control yourself, you yield yourself forever to this intoxication and never go further. Similarly, the other gifts are symbolic of the various siddhis attained by the seeker. If the seeker gets attached to such gifts and begins revelling in them, he will never get the ultimate prize.
Lakshmi, the Goddess of fortune chooses Vishnu (symbolic of the pure self) to be her own. The set of poisons that have to be endured before this happens, however, is equivalent to another stage of paradigm shift, though not as disturbing as the first one, since most of the work has already been done in this regard. But this shift has to be completed nevertheless. It is another stage of self-introspection, which is still somewhat difficult to deal with, but if the seeker comes out of it alright, fortune is on his side.
Dhanvantari, the physician (to be) of the Devas is the permanant good health (of the soul, not the body) attained after the final enlightenent. Fittingly, she carries the Amrita with her. Even at this stage, the bad can overcome the good and the entire journey would have been fruitless. This is shown by the asuras running off with the Amrita. How many times have we seen a great feat almost completed, but was not because the protoganists choked at the end? The presence of Mohini is the final distraction in this great feat. She can single-handedly trip you down if you have negative tendencies. The asuras cannot look at reason when they are infatuated, and are never able to get out of the grip of Mohini's charm. The Devas, in contrast, trust the Lord, and get the Amrita at the end. If you let the dark side become the dominant side, you end up much like the asuras did, deprived of the nectar. If you maintain control of your self like the Devas did, you are rewarded with immortality, and you can easily supress the negative tendancies that are present within you.
The final bit about Rahu attempting to get some of the Amrita is the statement that a wee bit of the negative tendencies lingers on. It is very easily controlled, and any attempt by it to enforce its superiority will soon fade out. From this new viewpoint, the story of the Coorma avatar is not just a story of the universe with a battle between the Devas and asuras, but a story about the self, about the process of enlightenment, about the pull of the good and bad sides. The moral is that letting the good flow throughout has its own rewards, and in fact, it brings about the ultimate reward - immortality.
# A digression:
The fact that our true self resides in pure consciousness is also represented in the depiction of Vishnu. Vishnu is always shown residing in the ocean of milk, resting on Anantha Sesha. Vishnu is the true self, residing in the ocean of pure consciousness, and his resting on Anantha Sesha is representative of the fact that you know your true self by gaining mastery over the kundalini energy.
Jaya and Vijaya are the gatekeepers of Vaikunta, Vishnu's abode, and due to a curse, they incarnated thrice each as evil beings - Hiranyakashipu and Hiranyaksha, Ravana and Kumbhakarna, and finally as Shishupala and Dantavakra. Their presence as the gatekeepers of Vaikunta is again symbolic of the fact that to get to the pure, calm self, you have to pass through chaos. Sort of like a highly compressed version of the Coorma avatar, but with the same essence.