Attending the festivals of the mushrikeen and congratulating them

Ibn al-Qayyim (may Allaah have
mercy on him) said: it is not permissible for the Muslims to
attend the festivals of the mushrikeen, according to the
consensus of the scholars whose words carry weight. The
fuqaha’ who follow the four schools of thought have stated
this clearly in their books… Al-Bayhaqi narrated with a
saheeh isnaad from ‘Umar ibn al-Khattaab that he said: “Do
not enter upon the mushrikeen in their churches on the day of
their festival, for divine wrath is descending upon them.”
And ‘Umar also said: “Avoid the enemies of Allaah on their
festivals.” Al-Bayhaqi narrated with a jayyid isnaad from
‘Abd-Allaah ibn ‘Amr that he said: “Whoever settles in the
land of the non-Arabs and celebrates their new year and
festival and imitates them until he dies in that state, will
be gathered with them on the Day of Resurrection.” (Ahkaam
Ahl al-Dhimmah, 1/723-724). 

With regard to congratulating
them on their festivals, this has already been answered in
Question no. 947, which
we advise you to refer to.