Being Jewish (and young), my boys know very little about Christmas celebrations, secular or otherwise. Particularly, they know next to nothing about Santa, which is just fine with me. In fact, I knew that I was on the right track when a well-meaning woman at the grocery store asked Oldest Son (age 5), "What do you want Santa to bring you this year?"
Oldest Son: Santa?
Woman: Yes, what's Santa going to bring you for Christmas?
Oldest Son: Oh, we don't celebrate Christmas. We celebrate Chanukah. And guess what? We get to light candles and sing songs and tell stories and read books and play dreidel. I love to play dreidel! I can spin it all by myself! I can't wait for Chanukah!
Woman: Oh. Well, Mery Christmas.
I didn't even care about her Christmas wish after hearing all about our Chanukah celebrations. What I loved was how excited he was and how he never mentioned presents (which we do very little of, admittedly).
This was all reinforced days later when Oldest Son saw a huge inflatable yard decoration of Santa's legs and feet sticking out of a chimney. Now, both of my boys refer to Santa as a snowman (man in the snow - makes sense), and I haven't bothered to correct them.
Oldest Son: Look! A red snowman is upside down in a laundry basket. That's silly! [laughs] Hey Eema (Hebrew for "Mom"), are we gonna get to play dreidel again this year?