Shaykh Muḥammad ibn Ṣāliḥ al-ʿUthaimīn said:

As for extending greetings to non-Muslims on their festivals, then this, without doubt, is forbidden and could, in some instances, be disbelief, as wishing them well on the occasions of their festivals shows one’s approval of them, and showing approval of acts of disbelief is itself an act of disbelief. This includes wishing them well on what is known as Christmas, or Easter and the likes. This is not permissible whatever the case may be. Even if they wish us well on our festivals we do not wish them well on their festivals. And the difference is that when they wish us well on our festivals, they wish us well for something that is right. Whilst if we were to wish them well on their festivals, we would be wishing them well for something that is wrong. This is the difference. We therefore do not say we are returning the gesture – if they extend greetings to us on our festivals we should not extend them greetings on their festivals, due to the difference mentioned earlier.

أما التهنئة بالأعياد فهذه حرام بلا شك، وربما لا يسلم الإنسان من الكفر لأن تهنئتهم بأعياد الكفر رضا بها، ورضا بالكفر كفر، ومن ذلك تهنئتهم بما يسمى عيد الكريسماس أو عيد الفُصْح أو ما أشبه ذلك، فهذا لا يجوز إطلاقاً حتى وإن كانوا يهنئوننا بأعيادنا فإننا لا نهنئهم بأعيادهم، والفرق أن تهنئتهم إيانا بأعيادنا تهنئة بحق، و أن تهتئتنا إياهم بأعيادهم تهنئة بباطل، هذا هو الفرق، فلا نقول إننا نعاملهم بمثل إذا يهنئوننا بأعيادنا فنهنئهم بأعيادهم للفرق الذي سمعتم.

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