It is different that a Muslim congratulating the celebration days of non-Muslims himself and congratulating the non-Muslim neighbors or friends on their celebration days.
It is not permissible for a Muslim to celebrate the religious days of non-Muslims, such as Christmas, Easter, passover etc. On the other hand, it is not wrong for a Muslim to wish those days to bring goodness to his non-Muslim acquaintance. Congratulating them on these special days does not mean internalizing those days. This is considered as for setting up good relations with non-Muslims.
For further information, see:
Relations with Non-Muslims: http://www.islamandquran.org/?p=1201