We threw in Christmas because we were hoping to appeal to Christians.  Since Christmas wasn't celebrated then the way it is celebrated today, we called them "Jesus Freaks."  I believe that was the term given to early Christians, but I need to confirm that with higher education types.  I think all cultures have always celebrated something in the Winter, so even if Hanukkah wasn't competing with proto-Christmas per se, there were other festivals in the air that contributed to the way Hanukkah came to be worshiped.  Christmas itself borrowed so much from pagan rites that it seemed to fit in the general solstice category.  Amichai Lau-Lavie has some interesting thoughts on this here.