Is it permissible to send a greeting card to my friend for Christmas?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

It is not permitted to send greeting cards for Christmas because scholars unanimously agree that it is prohibited to exchange greetings for the distinctive celebrations of disbelievers, as stated by Ibn Al-Qayyim. Similarly, exchanging greetings for birthday celebrations is also prohibited because it involves innovation in religion and imitation of disbelievers. In fact, Muslims only celebrate two feasts: 'Eed Al-Fitr and 'Eed Al-Adh-ha, in addition to the weekly one every Friday. Therefore, it is not permissible to celebrate or exchange greetings for any celebration other than these. 

Allaah Knows best.