Assuming they are Hindu it would be their bada din! Xmas has local versions in basically every country on earth. It's one of the only holidays that basically every human on this planet celebrates. Xmas is kind of turned into an amalgamation of every winter festival. Every country that's ever been touched by empire has ever had.

One of the really good things to ever come out of that era. Started kind of bad but with time it's allowed everyone to have a unified single holiday that we can all agree to be good to each other on while also giving everyone the ability to make it their own.

It's why it should be Xmas not Christmas. Because everyone can enjoy a mas.