Answer:
Yes it is!
Step-by-step explanation:
You can say "Merry Christmas!" to someone and it wont be offensive! IF they say that's not their religion, simply say "Happy Hanukkah!" If they don't celebrate that either, or the day at all, just simply apologize nicely and be on your way. (:
You could also say "Happy Holidays!"
Hope this helps!
And Merry Christmas!!