As an atheist (with a long, grueling fundamentalist, bible-believing background), I have no problem at all in wishing you a "Merry Christmas." It's no more tormenting to my atheist disbelief than saying, "It's Thursday," even though I don't believe in the Norse god Thor, or "It's Monday," even though many different languages, including English, associate the day with devotion to a moon deity. I rather like merriment of most every sort, even when steeped in superstition and mythology. In fact, religion is often helpful in throwing a little crazy into the mix. A party is a party, as I see it--though it is a shame that commerce has steadily choked any semblance of human spirit and liberty out of the holiday, dressed up Santa in Coca-Cola colors, and replaced twelve days of gambling and chasing skirt (December 25th to January 5th--ah, for a Pepysian Christmas again!) to a glee-less battle with long lines, heavy traffic, and purse-snatchers that lasts a whopping four weeks or more now (at the very least, taking Nordstrom's lead, from Black Friday to Christmas Day).
Oh, and how's this for a kicker? The pious picture above of the blessed virgin Mary and the baby Jesus was painted in 1913 by Adolf Hitler, who, at age 24, thought of himself as an artist and a devout Catholic. Frohe Weihnachten, holiday shoppers!
But, seriously, merry Christmas to all, especially to the poor, the ill, the lonely, the homeless, and those far away from a place they call home.