Thus it begins...
Imbalance between Good and Evil
The universal balance was maintained by Gods and Demons jostling with each other. But the Gods had started losing power after Rishi Durvasa had cursed Lord Indra for insulting him. As a result, the delicate universal balance between the forces of good and evil had been thrown off.
Consulting Lord Vishnu
Fearful that evil would permeate the world, the Gods pleaded with Lord Brahma for help. Lord Brahma knew that only Lord Vishnu, the preserver of creation, could guide the Gods. Led by Lord Brahma, the Gods approached Lord Vishnu for guidance.
Lord Vishnu, famous for his playful wisdom, suggested that the Gods and the Demons should get together and churn the ocean of milk called Ksheersagar to reveal the riches hidden in its depths. The Kumbh, or the pitcher of nectar thus revealed could help the Gods regain their lost strength.
Lured by the promise of the riches to be obtained by the churning, the Demons saw merit in the idea of forming an alliance with the Gods. The reason was that the effort required for the churning was too much for the Gods or the Demons alone. Thus, they struck a covenant with the Gods to share the objects revealed from the churning amongst themselves.
Thus began the churning of the ocean called 'Samudra Manthan'. The serpent king Vasuki was the churning rope, while the churning mace was the mighty mountain Mandara. Many otherworldly things, 14 in total, were generated by the churning. The Gods, however, were secretly waiting for the one coveted prize - Amrita, or the nectar of strength and immortality.
The last item to be revealed from the churning was Dhanvantari, the divine physician. He was carrying the pitcher of Amrit, called Kumbh. The Gods quickly seized it. To protect it from the Demons, Garuda, the mount of Lord Vishnu, flew away with it. The Demons, sensing that they had been tricked, followed in hot pursuit. For twelve days and twelve nights (equivalent to twelve human years) the Gods and the Demons fought in the sky for possession of this pot of Amrita.
A Tradition is Born
In this commotion, some drops of the nectar spilled on the earth at four places - Prayagraj, Haridwar, Ujjain and Nasik, and thus, one of the longest standing religious traditions in the world was born. It is believed that the drops infused the waters with the same Amrita, which not only could heal and make well, but also wash away a person’s sins and thus help him or her along the path to salvation.
The Demons were quite mighty and the weakened Gods were proving to be no match for them. Concerned that the Demons would drink the nectar and establish dominance over the universe, Lord Vishnu assumed the form of Mohini, a celestial Apsara of divine beauty, and asked the Gods and Demons to sit in separate rows and offered to feed a drink of the nectar to them. Enchanted by the celestial beauty before them, the Demons agreed. However, Mohini started with feeding Amrit to the Gods and as soon as the Gods were fed, disappeared. The Demons were enraged at the deception but were driven away by the rejuvenated Gods, and balance was restored in the universe. As Amrit or the nectar of immortality is also called 'Sura', the Demons came to be called 'Asuras', or the ones devoid of the nectar.