Overview
Diwali in Jainism marks the anniversary of Nirvana (final release) or liberation of Mahavira's soul, the twenty-fourth and last Jain Tirthankara of the present cosmic age. It is celebrated at the same time as the Hindu festival of Diwali. Diwali marks the end of the year for Jains, and it likewise commemorates the passing of their twenty-fourth Tirthankara Mahavira and his achievement of moksha.
History
Mahavira attained Moksha (liberation) on this day at Pawapuri on 15 October 527 BCE, on Chaturdashi of Kartika, as confirmed by Tilyapannatti of Yativrsabha.
Mahavira, the 24th Tirthankara of this era, revitalised Jain dharma. According to tradition, the chief disciple of Mahavira, Ganadhara Gautam Swami also attained omniscience i.e. absolute or complete knowledge (Kevala Jñāna) on this day, thus making Diwali one of the most important Jain festivals.
Mahavira attained his nirvana at the dawn of the amavasya (new moon). According to the Śvētāmbara text Kalpasutra, many gods were present there, illuminating the darkness. The following night was pitch black without the light of the gods or the moon. To symbolically keep the light of their master's knowledge alive:
From Wikipedia (CC BY-SA 4.0).