When a jew tries to jew you down, why risk career destruction by yelling back "filthy kike" or "Heil Hitler"? Simply cheerfully wish him "Merry Christmas". To the jew, it's one of the most offensive epithats and when used by an educated goy, a sign of feared goyish resistance.

Furthermore, make sure that you always refer to Christmas and not "the holidays", ie, Christmas party, Christmas vacation, Christmas shopping, Christmas present, Christmas card, etc. This isn't about religion; it's about cultural solidarity versus the invasive alien jew.