Not always knowing the other person's persuasion or anything about their holiday, I stick to my own holiday and hope they take it the right way.
If one does not not know what holiday a person celebrates, why feel compelled to comment one way or the other? I never wish Merry Christmas to people unless I know they are Christians. I never would wish someone "happy" Ramadan unless I knew they were moslem and knew if it was appropriate to do so.
Celebrating someone else's holiday is well,,,goofy. Wishing them well on the one they celebrate makes perfect sense if it is genuine.