Within the last few days, we’ve seen protestors holding crosses shout “go home!” at Muslims in front of the Oklahoma State Capitol, several Idaho state senators refuse to listen to a Hindu invocation, and new poll numbers suggesting that a majority of Republicans -- 57 percent -- “support establishing Christianity as the national religion.”

In a year already filled with attacks and harassment of religious minorities across the country, the rise of such “Christian nation” rhetoric is troubling. But it’s not new.

No mere assessment of the religious affiliations of population, the argument that America was at its founding and remains a nation Christian in character has served as cover for a variety of racist and nativist sentiments for generations. It can be found in the writings of those who warned that Catholics threatened the nation’s “free institutions” and fanned the flames of a mob’s destruction of a New England convent in 1834, just as it can been seen decades later in newspaper reports warning that non-Christian Asian immigrants would cause the West Coast to be “swamped, inundated, despiritualized, and un-Americanized.”

The insistence that the United States is explicitly Christian arises from the assumption that a majority of citizens have been members of one church or another since the nation’s founding. Yet historians have estimated the number of American church-goers in 1776 to be only around 350,000 -- less than a fifth of the population.     

Christianity as a cultural force was certainly more influential than that, and many Americans no doubt considered themselves Christians whether or not they attended church. But it is a fact conveniently forgotten by many that ministers from a variety of denominations were from the beginning among the strongest opponents to establishing a national religion of any kind.

Even as a matter of demographics, “Christian nation” raises questions. A large number of the people who we now as acknowledge as Americans often go uncounted when we look at back at our country’s earliest days.

More than a hundred thousand Native Americans, mostly unconverted before the Trail of Tears, were pushed beyond the borders of the United States with the Indian Removal Act of 1830.

That same year, the enslaved population numbered in the millions—in much of the South, they made up half the population. Given that only a tiny percentage of the enslaved were Christians when they arrived, early America likely included more men and women with connections to African beliefs than members of many Protestant denominations. What do these uncounted non-Christians do to the idea that America began as a “Christian nation”? 

Just two months into 2015, vandalism has been directed at mosques and temples in Rhode Island, Texas, and Washington. Anti-Muslim rhetoric has grown particularly loud, and has been heard in places as geographically and politically distant as California and North Dakota. 

While some of the incidents making up this trend may be bald racism dressed up in religious garb, and others may have grown out of misdirected responses to news of atrocities committed by ISIS and other extremist groups, they all are now part of a more complicated history: Islam today plays a role in American culture previously occupied by other supposedly foreign beliefs.

Every generation finds its own religious bogeyman -- strange ways from afar that seem to threaten safety and stability at home. It might be said that the widespread fear now seen as a response to Islam has been with us all along. Fear is the constant; the beliefs that inspire it change over time.  

Moments of heightened collective anxiety through much of the nation’s history could be presented as a progression of religiously-fueled hysterias. From rampant anti-Catholicism and “Yellow Peril” suspicion of Chinese temples in the nineteenth century, to the twentieth century’s open anti-Semitism, forgotten anti-Hindu and Sikh obsession, and World War II-era targeting of Japanese Buddhists by the FBI, as a people we have been repeatedly convulsed by the notion that spiritual differences might be our undoing.  

Each of these spasms of violence and suspicion was shaped by the particular era of American history in which it occurred, but they all had one thing in common: the stubborn idea that the United States is a “Christian nation.”

No doubt many Americans who consider their citizenship and their religious identity entwined do so with no motive other than wanting to see their personal stories represented in their country’s history. And in fact, the First Amendment’s guarantee of freedom of religion makes this truth possible for all.

Yet both today and in a past far more religiously diverse than usually remembered, the insistence that America is a Christian nation has too often encouraged incidents that might be described not only as un-American, but un-Christian as well.

No matter how many Christians live here, we are not a Christian nation. For the sake of people of all faiths and of no faith, we should hope we never become one.

Peter Manseau is the author most recently of "One Nation Under Gods: A New American History" (Little, Brown and Company January 2015).