Great to see this from a Muslim leader. https://twitter.com/ImranKhanPTI/status/1327442599028854784

Muslims do not celebrate non-Muslim religious festivals like Diwali or Christmas, but our Prophet taught us to be neighbourly, and part of this is wishing well to those of other faiths on their holy days.

This is a well-regarded position among contemporary Islamic scholars, e.g. European Council for Fatwas, Dar al-Ifta in Egypt, Dar al-Ifta in Jordan.

https://www.dar-alifta.org/ar/ViewFatwa.aspx?sec=fatwa&ID=13259&%D8%AA%D9%87%D9%86%D8%A6%D8%A9_%D8%A7%D9%84%D9%85%D8%B3%D9%8A%D8%AD%D9%8A%D9%8A%D9%86_%D9%81%D9%8A_%D8%B9%D9%8A%D8%AF%D9%87%D9%85

Of course, there is legitimate difference of opinion among the ulama on these matters (e.g. from some Saudi and Qatari scholars and institutions). Under such circumstances, the usual rules regarding juristic disagreement apply.

As a general rule, where there are divergent but authoritative fatwas, a layperson or nonspecialists is permitted to follow whichever opinion they feel most comfortable with, religiously speaking, but they should avoid criticising those who follow another authoritative opinion.