Ahh, it's that time of year again. It's a little colder, you have to start worrying about which photo to choose for your holiday card, and you can't step foot in a department store in America without being greeted by the sound of toddlers fussing while waiting in long lines with their stressed-out parents as Mariah Carey tell us repeatedly over the loudspeaker what she wants for Christmas.

(Spoiler alert: it's you.)

When you finally reach the cash register, after listening to the woman in front of you tell little Jonathan to use his "inside voice" five or six times, the cashier rings you up and hands you a receipt with a weary smile and a rehearsed-yet-chipper "Merry Christmas!"

If you fall under the 90 percent of Americans that celebrate Christmas, according to a study conducted by the Pew Research Center earlier this month, then you won't think anything of this. However, if you're in the 10 percent of Americans who doesn't, a random stranger wishing you a "Merry Christmas" could easily be jarring, alienating and a little rude.

Before you think "Oh, but 10 percent isn't that many," consider this: according to the constantly-updating U.S. and World Population Clock, which is operated by the United States Census Bureau, at the time of writing, the U.S. is home to 326,424,710 people. (But according to the clock, there's a new birth every eight seconds, so by the time you read this, that number will be slightly different.)

Because the U.S. is currently home to 326,424,710 people, and 10 percent of Americans don't celebrate Christmas, that means that more than 32 million people in America don't celebrate Christmas.

That's a lot of people.

The thing is, unless you personally know the person you're saying "Merry Christmas" to, you actually have no idea whether they celebrate Christmas or Hanukkah or both or something else or nothing at all. So, if you work in a department store, an ice cream store, a photo printing lab, a bar, etc., and you wish a patron a "Merry Christmas," you have absolutely no idea where they're from or what they're about.

Take me, for example. I'm Jewish-American, but my family and I put up both a Christmas tree and a menorah every year, mostly because it's fun. We celebrate both, but don't go all-out with either. I've never been to church, I hate Christmas music more than any other kind of music on this planet, and on December 25, you'll find me and my family at the local Chinese restaurant along with all the other Jews. (Since Chinese restaurants are typically one of the few eating establishments that stay open on Christmas.)

Even though I technically celebrate Christmas, I still feel a little pang of annoyance whenever someone I don't know wishes me a "Merry Christmas," because for all they know, I only celebrate Hanukkah. Or nothing at all.

Obviously, wishing someone a "Merry Christmas" is supposed to be a nice thing to say to someone. Instead, if you don't know someone, stick to "happy holidays" for an in-person greeting and "season's greetings" for holiday cards. These sayings are all-encompassing, and that way, nobody feels left out. And bringing people together is what the holidays are all about.