"America was born a Christian nation," echoed Woodrow Wilson. Harry Truman affirmed it: "This is a Christian nation."
But in 2009, Barack Hussein Obama begged to differ: "We do not consider ourselves a Christian nation."
Comes now a Pew Research Center survey that reveals the United States is de-Christianizing at an accelerated rate.
Whereas 86 percent of Americans in 1990 identified as Christians, by 2007, that was down to 78 percent. Today only 7 in 10 say they are Christians. But the percentage of those describing themselves as atheists, agnostics or nonbelievers has risen to 23. That exceeds the Catholic population and is only slightly below evangelicals.
Those in the mainline Protestant churches -- Presbyterians, Lutherans, Methodists, Episcopalians -- have plummeted from 50 percent of the U.S. population in 1958 to 14 percent today. By accommodating the social revolution of the 1960s to stay relevant, mainline churches appear to have made themselves irrelevant to America's young.
The decline in Christian identity is greatest among the young. While 85 percent of Americans born before 1945 still call themselves Christians, only 57 percent of those born after 1980 do.
If we want to see our future, we should probably look to Europe, where Catholic Ireland just voted in a landslide to legalize same-sex marriage and where cathedrals and churches are being turned into tourist attractions and museums and even bars and restaurants.
What are the causes of a de-Christianized America?
High among them is the Supreme Court, which, since the Earl Warren era began, purged Christianity from all public schools and the public square -- and has been met with a puzzling lack of resistance from Middle America to the secularist revolution being imposed upon it.
Second, an anti-Christian elite captured the cultural heights -- the arts, elite universities, popular culture, the media -- and began, through movies, books and magazines, an assault on Christian beliefs and morality.
Third was the social revolution of the 1960s, which began with the arrival of the baby boomers on campus in 1964. Five years on, Woodstock Nation was wallowing in the mud, listening to Country Joe & the Fish.
The counterculture of the '60s would be used as a foil to build 49-state landslides for Richard Nixon and Ronald Reagan, but then the '60s views and values were embraced by the elites and came to dominate the culture in the time of Bill and Hillary Clinton. Given his baggage, "Slick Willy" of Yoknapatawpha County would have been a comic figure in the 1950s. Today he is the Democratic Party's beau ideal of a statesman.
Many churches came out to meet the cultural revolution halfway. The results were irrelevance and scandal -- too many Elmer Gantrys in televangelist pulpits and too many predators in priestly cassocks.
What are the consequences of a de-Christianized America and West? Si monumentum requiris, circumspice. (If you would seek its monuments, look around you.)
Half of marriages end in divorce. Fewer children are being born, and of these, over 40 percent are out of wedlock. Record drug use rates and dropout rates and soaring crime rates that have declined only because we have an incarceration rate that rivals South Africa's.
Despite astonishing advances in medicine, we have far more and far more varied and deadly STDs.
As Christianity dies, individualism, materialism and hedonism replace it. "Selfies" could be the name for the generation for whom Easter Sunday long ago took a back seat to Super Bowl Sunday. More than a million abortions a year, assisted suicide and euthanasia are seen as the milestones of social progress in the new America.
"Panem et circenses," bread and circuses, were what the late Roman Empire was all about. With us, it is sex, drugs and rock, with variations on all three.
Historically, as the faith dies, the culture and civilization to which it gave birth die, and then the people die. And a new tribe with its own gods comes to occupy the emptying land.
On the old and new continents, it is the native-born of European ancestry who are de-Christianizing, aging and dying. And the nations they created are the ones depopulating.
To occupy Rome, the barbarians came from the east and north. To occupy the West, they are coming from the south. And like the Romans of the fourth century, we seem paralyzed and powerless to stop them.
Christianity was the founding faith of the West. That faith and the moral code and culture it produced once united this disparate and diverse nation and civilization.
As Christianity fades away and the moral code and culture it generated recede into irrelevance, what will hold us together?
Economically, we are dependent on foreigners for the necessities of our national life. Our politics are poisonous. Our racial divisions, once ameliorated by shared belief in the same God and Bible, are rawer than they were in the 1950s.
As for equality, diversity and global democracy, who will march and die for that?
Historian Arnold Toynbee said it well: "Civilizations die from suicide, not by murder."