In recent years, the debate over whether to say “Merry Christmas” or “Happy Holidays” has become as reliable a post-Thanksgiving tradition as the Black Friday shopping craze.

Like many issues these days, the great holiday greeting debate tends to separate along political lines as much as religious ones. According to a poll conducted by the Public Religion Research Institute in 2016, 66 percent of Democrats said that stores and businesses should greet customers with “Happy Holidays,” “Season’s Greetings” or some other general greeting, rather than “Merry Christmas,” as a show of respect for different religious faiths; only 28 percent of Republicans felt the same.

Setting aside politics, what’s the history behind the different greetings? How did a simple salutation get so controversial?

Much like “Merry Christmas,” it turns out that “Happy Holidays” also has religious roots. Both are derived from Old English: Christmas comes from “Cristes Maesse,” or the Mass of Christ, the first usage of which (in 1038) described the mass held to commemorate Christ’s birth. As for “holiday,” the word emerged in the 1500s as a replacement of the earlier medieval word “haliday,” which itself had supplanted the Old English “haligdæg,” meaning holy day.

Recently, an investigation into the history of the phrase “Happy Holidays” as a seasonal greeting in the United States by self-described history nerd Jeremy Aldrich turned up its usage as early as 1863, in the Philadelphia Inquirer. By the middle of the 20th century, the phrase was well established in popular usage, as shown in a study of ads run by the R.J. Reynolds Tobacco Company of Winston-Salem, North Carolina, in Carolina Magazine from 1935 to 1942 to encourage giving the gift of tobacco.

A 1937 ad proclaimed: “A gift of Camels says, ‘Happy Holidays and Happy Smoking!’” Other ads from the 1930s and early 1940s stuck to “Season’s Greetings,” but all featured jolly, grinning Santa Clauses, reindeer, Christmas trees and other recognizable Christmas symbols.

As Andrew McGill wrote in The Atlantic in 2016, Christians have exchanged the greeting “Happy Holidays” among themselves for decades, most with the understanding that the “holidays” meant the season of Advent, the four-Sunday cycle on that includes Christmas and ends on the Feast of the Epiphany. But Christmas turned from a religious occasion to a largely secular one for many people, the phrase “Happy Holidays” also expanded its usage, becoming a more universal greeting used to include people of various religions, and even a nod to the New Year.

Controversy over phrasing rarely figured in to historical presidential holiday greetings. In the book Season’s Greetings From the White House, first published in 1996 and updated in 2007, author Mary Evans Seeley offers details of presidential Christmas cards, messages and gifts through the years. Back in the 1950s, her research shows, Dwight D. Eisenhower’s holiday cards read “Season’s Greetings.” Later presidents, from John Kennedy and Lyndon Johnson to Ronald Reagan and Bill Clinton, also tried not to alienate non-Christians in their holiday missives.

But in 2005, just as the idea of a “War on Christmas” was gaining momentum in conservative circles, critics spoke out against President George W. Bush’s omission of the word “Christmas” from his White House holiday card. At that time, Seeley told the Washington Post that the last time a presidential holiday card had mentioned Christmas was 1992, during the administration of Bush’s father, George H.W. Bush.

The great holiday greeting debate doesn’t seem to be reflected in the history of greeting cards themselves, which have a long tradition of varied offerings for the holiday season. Hallmark, founded by J.C. Hall in 1910, started producing its own greeting cards in 1915.

“The company’s first line of Christmas cards prominently featured the sentiments ‘Merry Christmas,’ ‘Christmas Greetings’ and ‘Season’s Greetings’ on the front of each design,” says Samantha Bradbeer, archivist and historian for Hallmark Cards, Inc. Other sentiments, such as “Joyful Greetings” and “Yuletide Greetings” also appeared on early 20th century cards, Bradbeer explains, but they weren’t as frequently used as the Christmas greetings.

Over the years, Hallmark has expanded its options to reflect consumer trends and incorporate more religious and cultural backgrounds; Hanukkah cards were added in the 1950s, and Kwanzaa greetings were introduced in the 1990s.

On greeting cards, Starbucks coffee cups and in everyday conversation, history shows people have chosen from a diverse selection of ways to express goodwill around the holiday season. So while the debate over appropriate holiday greetings shows no signs of being resolved any time soon, there’s one thing we can all keep in mind. Whether you choose to say “Merry Christmas” or “Happy Holidays,” sincerely wishing someone else well at this time of year—or any time, really—is never a bad idea.