Editor's note: Randall Balmer, an Episcopal priest, is professor of American religious history at Barnard College, Columbia University, and a visiting professor at Emory University. His most recent book is "God in the White House: How Faith Shaped the Presidency from John F. Kennedy to George W. Bush." Randall Balmer supports Obama's unusual broadening of a president's words to include nonbelievers. NEW YORK (CNN) -- President Obama's mention of "nonbelievers" in his inaugural address represents an important broadening of the circle of acceptability in American life, an acknowledgement of our growing diversity and a fuller embrace of the principles articulated in our nation's charter documents.
@highlight
Randall Balmer: It's unusual for a president to include nonbelievers in his words
@highlight
He says America has widened its circle of religion for hundreds of years
@highlight
Balmer says rhetoric has grown to include Jews, Muslims, Hindus
@highlight
The First Amendment makes it appropriate to recognize nonbelievers, he says
The story of religion in @placeholder life has been one of expansion and ever-increasing diversity.