The view of Ahlus Sunnah wal-Jamaa`ah since the time of the Four A'immah (Imaam Abu Haneefah, Imaam Maalik, Imaam ash-Shaafi`ee, Imaam Ahmad ibn Hanbal) has been that celebrating the holidays of the Kuffaar is Haraam. There are only two views with regards to celebrating the holidays of the Kuffaar:
1) It is Kufr.
2) It is Haraam.
The most lenient view in this regard is that the one who does so has committed a Haraam act but has not become a Kaafir.
There is no view of permissibility, among Ahlus Sunnah wal-Jamaa`ah.
The view that it is permissible to celebrate Christmas, etc. is a view that Shaytaan invented a few years ago and inspired to his followers. It is a view which opposes the Qur'aan and the Sunnah. The Mufassiroon of Islaam for 1,438 years have Ijmaa` that the Aayah of the Qur'aan: "والذين لا يشهدون الزور
" (those who do not take part in az-Zoor), that "az-Zoor" refers to the holidays and celebrations of the Kuffaar.