illustration (attribution, if any possible, is at the end of the article)
Diwali is a Hindu celebration, the end of the harvest season in most of India and thus the appropriate time to thank the Gods for the recent harvest and pray for a good harvest for the year to come. Regional variations might add other connotations (e.g. in Gujarat, it is immediately followed by "new year").
But this is shared with other traditions:
• Jains celebrate the attainment of moksha or nirvāṇa by Mahavira, the last of the Tirthankar of this era,
• Sikhs celebrate the release from prison of Guru Hargobind, the sixth guru…
'Diwali' is a contraction of deepavali (दीपावली), "row of lamps". It traditionally involves the lighting of diyas, small clay lamps filled with oil, to signify the triumph of good over evil. Firecrackers keep evil spirits at bay.
The lamps are kept on during the night and one's house is cleaned, both done in order to make the goddess Lakṣmī feel welcome.
Given the link of this celebration with harvest, it is no surprise that Lakṣmī is the goddess of wealth, prosperity (both material and spiritual), fortune… but Lakṣmī is also the wife of Vishnu, and while she might be celebrated on this day for welcoming the return of Vishnu to his 'Vaikuntha' abode after the Vamana avatar, it happens that a later avatar of Vishnu (according to Hinduism) is… the Buddha!
From a buddhist perspective, seeing the Buddha as an avatar of Vishnu (rather than a human being) might appear as a sign of 'ignorance', but one should be mindful not to forget selflessness… Assuming too 'solid' a separation between the Buddha and Vishnu, or even between human and godly 'form', might not be "orthodox Buddhism" either!
And buddhists don't need to be upset by the 'appropriation' of 'their' Buddha by Hindus, when the latter conceive the Buddha as an avatar of one of their greatest gods… Buddhists should be able to appreciate this sign of respect (and remember that the Pāḷi Canon appropriated Brahma and Māra…).
We can focus on what brings us together…
photo: Vishnu and Lakshmi on Shesha Nāga
(with several iconographic elements the buddhists will recognise)