Significance
Kartik Purnima is one of the holiest full moons in the Hindu calendar. Lord Vishnu is said to have defeated the demon Tripurasura on this day as Tripurari (Shiva). Bathing in sacred rivers on Kartik Purnima carries the merit of a thousand Ashvamedha Yajnas. In Varanasi, thousands of lamps are floated on the Ganges in the Dev Deepawali celebration. Simultaneously, this full moon marks the birth anniversary of Guru Nanak Dev Ji -- the founder of Sikhism and a saint revered across the dharmic traditions as a messenger of love, equality, and the Divine Name (Naam).
Preparation
Rituals & Vidhi
Sacred Bath at Dawn
Bathe before sunrise, preferably in a river, chanting the names of Vishnu. Mix sesame seeds in the bath water for added merit.
Mantra: Om Namo Bhagavate Vasudevaya
Vishnu Puja
Offer Tulsi, white flowers, and Panchamrit to Vishnu. Recite the Vishnu Sahasranama or Satyanarayan Katha.
Dev Deepawali Lamps
At dusk, light clay diyas and float them on a river, pond, or even a large tub of water. This illuminates the water in honor of the devas celebrating Vishnu's victory.
Gurudwara Visit
Visit the Gurudwara for the Guru Nanak Jayanti celebrations -- participate in Akhand Path readings, kirtan, and the langar (community meal).
Family Guidance
This is a perfect day to introduce children to the universal spirit of dharma that connects all traditions. Visit both a temple and a Gurudwara. Discuss Guru Nanak's core teachings: Naam Japo (remember the divine), Kirat Karo (honest work), Vand Chhako (share with others).