One of my Jewish friends greets me with “Happy Hanukkah” this time of year. I’m honored, not offended. And she doesn’t (seem to) mind my “Merry Christmas” greeting. Nothing wrong with recognizing someone else’s special holiday and nice to include each other.
“Ba humbug” is probably a good reply if you don’t like being included in their holiday and don’t want to hear the greeting again.
My Jewish and Muslim friends celebrate Christmas. They think it is just part of America.