What is the ruling on congratulating disbelievers on their holidays?

Congratulating disbelievers on their religious holidays, such as Christmas, is impermissible by consensus, as it involves an affirmation of the rituals of disbelief and a رضا (acceptance) of them. Whoever does so exposes themselves to Allah's wrath and displeasure. It is not permissible to respond to their congratulations on their holidays, just as it is forbidden to imitate them by holding parties or exchanging gifts on this occasion. Whoever does any of that is a sinner.