Like all delusions, this one contains a kernel of truth. The percentage of Americans who identify with no formal religion, including a minority who call themselves atheists and agnostics as well as those who simply belong to no congregation, has indeed been growing steadily. Between 2007 and 2014 alone, the number of religious “nones” rose to 23 percent from 16 percent of the adult population, according to the Pew Research Center.

But American history offers scant support for the belief that religion makes for more tolerant, gentler politics. American Christians were long divided over whether slavery was a moral abomination or was blessed by the God of the Bible, and our politics was never meaner than in the two decades preceding and following the Civil War. Religious Americans, then as now, held widely varying political views. Today, the bitter dispute over women’s reproductive rights can best be understood as a moral argument that has never been resolved in religion or politics.

As an atheist and a political liberal, I object most strongly to the argument that politics must be a substitute for faith because everyone needs religion.