Opening Of The "Vaikuntha Dwaram"

According to Vishnu Purana, fasting on Vaikuntha Ekadashi is equivalent to fasting on the remaining 23 Ekadashis of the Hindu year.However according to Vaishnava tradition fasting is mandatory on all Ekadashi's. Fasting on Ekadashi is considered holier than any other religious observation.
 
Lord opened the gate of Vaikuntham (his abode) for two demons in spite of them being against the Lord. They also asked for the boon that who ever listens to their story and see the image of Lord coming out of the door (called Dwar) called Vaikunth Dwar they reach Vaikunth as well. Temples all over India make a door kind of structure on this day for devotees to walk through.
According to Padma Purana, the female energy of Lord Vishnu slayed the demon Muran and protects the `Devas'. This happened on the eleventh day of lunar month during the sun's journey in the Dhanur rasi. Impressed by the act, Lord Vishnu names her as `Ekadashi' and gives her the boon that those who worship `Ekadashi' on the day of her victory over Muran would reach  His abode Vaikuntham.

Vaikuntha Ekadasi is one of the important and auspicious days for Hindus. It is dedicated to Lord Vishnu. It occurs in the Hindu calendar, in the month of Margashirsha (Between December and January).When observed, it bestows liberation from the cycle of birth and death.

It is important to look at the significance of this auspicious day from the spiritual angle.The demon Muran stands for the rajasic and tamasic qualities in people, which attributes to lust, passion, inertia, arrogance etc. When one conquers these tendencies, one attains the purity of mind, Sattva, indispensable for attaining moksha, liberation or realisation of the self.

For realising the self as pure awareness, purity of mind is required. Fasting helps to keep tendencies at bay, which could be triggered by intake of certain food. Keeping vigil in the night is symbolic of awareness, or being watchful of the contents of the mind. When the mind is looked at, it becomes still. To abide in the stillness is to attain freedom or peace, acquired through merging of the mind with the self. This is symbolic of the mind automatically being absorbed at the sight of the Lord after the arduous fast and vigil.

The belief that rice is prohibited, because Muran dwells in it, symbolically signifies the fact that eating of rice could get one feel heavy and hamper the vigil to be kept up. This signifies that entertaining negative tendencies could hamper one's progress towards awareness or consciousness.Observance of the rituals on this auspicious day even without understanding its importance is beneficial. Hence the merits accrued through observing it with piety is believed to be immeasurable.

In Mahabarata, Bhagavad Gita - the conversation between Lord Krishna and Arjuna at the beginning of Kurukshetra War is said to have occurred on this day.