In a world encouraged to embrace differences, BC and AD are increasingly on the wrong end of the religious sensitivity meter.
Educators and historians say schools from North America to Australia have been changing the terms Before Christ to Before Common Era and Anno Domini (Latin for year of the Lord) to Common Era. In short, they're referred to as BCE and CE.
The change has stoked the ire of Christian conservatives and some religious leaders, who view it as an attack on a social and political order that has been in place for centuries. Ironically, for more than a century Hebrew lessons have used BCE and CE, with CE sometimes referring to Christian Era.
That begs the question: Can old and new coexist in harmony, or must one give way to the other to reflect changing times and attitudes?
The terms BC and AD have clear Catholic roots. Dionysius Exiguus, an abbot in Rome, devised them as a way to determine the date for Easter for Pope St. John I. The terms were continued under the Gregorian Calendar, created in 1582 under Pope Gregory XIII.
Although most calendars are based on an epoch or person, BC and AD have always presented a particular problem for historians: There is no year zero. Critics say that's additional reason to replace the Christian-based terms.
"When Jews or Muslims have to put Christ in the middle of our calendar ... that's difficult for us," said Steven M. Brown, dean of the William Davidson Graduate School of Jewish Education at the Jewish Theological Seminary in New York City. "They are hard for non-Jews, because they assume a centrality of Jesus ... it's not offensive, but it's not sensitive to my religious sensibilities."
The new terms were introduced by academics in the 1990s in public elementary and high school classrooms.
"I started using BCE when some of my students began asking more earnestly than before just what BC meant," said Bill Everdell, a history book editor, teaching instructor and Brooklyn history teacher in the private, formerly religious St. Ann's School. Everdell said most history teachers he knows use BCE and CE. "I realized the courtesy was mine to extend."
He said the national Advanced Placement test in history has used the new terms since 2001.
In New York, the terms are entering public classrooms through textbooks and worksheets, but BCE and CE are not part of the state's official curriculum and there is no plan to debate the issue, said state Education Department spokesman Jonathan Burman.
"The standard textbooks primarily used in New York use the terms AD and BC," Burman said. Schools, however, may choose to use the new terms, although BC and AD will continue to be used in the state Regents exams, many of which are required for high school graduation.
Candace de Russy, a national writer on education and Catholic issues and a trustee for the State University of New York, doesn't accept the notion of fence-straddling.
"The use of BCE and CE is not mere verbal tweaking; rather, it is integral to the leftist language police -- a concerted attack on the religious foundation of our social and political order," she said.
"Has anyone actually been oppressed by the use of BC and AD?" de Russy said. "And do not BCE and CE implicitly refer to Christ? That is, when did the common era begin, after all?"
For centuries, BC and AD were used in public schools, universities and in historical and most theological research. Some historians and college instructors started using the new forms as a less Christ-centric alternative.
"I think it's pretty common now," said Gary B. Nash, an emeritus professor of history at UCLA and the director of the National Center for History in the Schools. "Once you take a global approach, it makes sense not to make a dating system applicable only to a relative few."
But not everyone takes that pluralistic view.
"I find it distressing, I don't like it," said Gilbert Sewall, director of the American Textbook Council, which finds politics intruding on instruction. He said changing terms accepted for centuries because of a current social movement such as multiculturalism could threaten other long-held principles.
Nash said most major textbook companies have adopted the new terms, which are part of the national world history standards.
But even those standards have been called into question.
"Is that some sort of the political correctness?" said Tim Callahan of the Professional Assn. of Georgia Educators, an independent group with 60,000 educator members.
"It sounds pretty silly to me," Callahan said of the use of BCE and CE.
In a 2000 resolution, the Southern Baptist Convention condemned the new terms as "the result of the secularization, anti-supernaturalism, religious pluralism, and political correctness pervasive in our society."
Ben Johnson, a Latin teacher at Hampden Academy, a public high school in Hampden, Maine, finds himself in the middle of the debate. Johnson, 26, sticks with BC and AD, and said so in a posting on the Internet. But he also allows students, and anyone else, to use either.
"Political correctness can sometimes go a little too far, and maybe that's what's happening," Johnson said.