Look, It's not all about you.

Cafepress

A man was waiting to board United flight 1140 to Dallas at La Guardia airport when a cheerful gate attendant wished him a Merry Christmas.  The passenger took offense:

“You shouldn’t say that because not everyone celebrates Christmas.” The agent replied, “Well, what should I say then?”“Don’t say, ‘Merry Christmas!’ ” the man shouted.

Yes, you guessed it, upon boarding the plane the man was greeted by a flight attendant with... "Merry Christmas".

“Don’t say, ‘Merry Christmas!’ ” the man raged before lecturing the attendants and the pilot about their faux pas. The crew tried to calm the unidentified man, but he refused to back down and continued hectoring them. He was escorted off the plane as other fliers burst into cheers and applause.

NYPost 

Author Tom Wolfe dubbed the Baby Boomer's "The Me" generation back in the 70's.  Boy was he wrong, of course he didn't have people today to compare them to.  

"Merry Christmas" is simply someone wishing you well, it doesn't require you to believe in God, it doesn't require you to believe in Christmas... it's nothing more than a sentiment, someone wishing you good cheer, good morning, good afternoon, good evening, or good night.

These sentiments do no harm, the better among us really mean them, some among us could care less whether you're merry or not, they are simply people being polite and it is nothing more than etiquette.  

I've been wished Happy Hanukkah, Ramadan Mubarak, I've even been wished a Bright Diwali.  None of this demeans or diminishes me in anyway, it is not a threat to my beliefs or world view.  Take it for what it is... warm wishes.

AND GET OVER YOURSELF