Leftists are chipping away at America’s ideals and exacerbating the same polarization for which they blame conservatives. They are undermining the nation’s shared history and its commitment to civil discourse. The resulting balkanization will cause alienated Americans to resort to self-imposed segregation and support strident political leaders who promise to fight back.

In a speech before the Civil War, the radical preacher Theodore Parker popularized “the American idea.” Parker’s recipe combined three ingredients: All people are created equal, all possess unalienable rights, and all Americans should have the opportunity to develop them. An abolitionist, Parker believed in one inspired American culture, supported by all Americans, and open to all Americans.

Leftists rightfully emphasize the “open to all” component, arguing for diversity and equality for the disenfranchised, but they neglect the “one shared American culture.” Diversity thus becomes division, as the left works to undermine America’s civic religion.