Curiosity question, do the Lefties treat you with the same respect?
The reason I ask is that I have BIL who manages to get one last dig in every year in the Christmas letter he sends out.
Only my relatives and close friends know my political positions on things, and they just "tolerate" me as a result. Most of the "friends" I have on FB are old co-workers, school mates, models (I do glamour photography now) and they don't know from my posts what my positions are. I get work from FB (photography), so I don't want to burn bridges that way.
You should reply and thank him for honoring the birth of Jesus.