Muslims should believe in all the Messengers of Allah and they should love all of them. This is clearly stated in the Qurâ€™an. Allah Almighty says: [The messenger believeth in that which hath been revealed unto him from his Lord and (so do) the believers. Each one believeth in Allah and His angels and His scriptures and His messengers We make no distinction between any of His messengers and they say: We hear, and we obey. (Grant us) Thy forgiveness, our Lord. Unto Thee is the journeying] (Al-Baqarah 2:285).
Accordingly, there is no harm in receiving a cash bonus from your employer on the occasion of Christmas. However, you should use the money according to the teachings of Islam. In other words, you should not buy any prohibited items with that money. This is not a transgression to the Qur'an or the Sunnah. But it is a donation that you didn't ask for, therefore you are recommended to accept it and spend it in good causes.