More than 220 people from more than 40 countries participate in the Fiesta of Independence Naturalization Ceremony at South Mountain Community College in Phoenix on July 4. (Carolyn Van Houten/The Washington Post)

Are you American?

What do you think about when you answer this question? Do you think in terms of citizenship? Cultural attributes? Certain values?

When Grinnell College, where we are both faculty members, polled Americans on what they most associate with being a “real” American, the vast majority of respondents identified a set of values as more essential than any particular identity.

Ninety percent said treating people equally is very important to being a “real” American. Eighty-eight percent said it included taking personal responsibility for one’s actions. Accepting people of different racial (81 percent) and religious (78 percent) backgrounds also ranked very high.

We found the widespread support for these core values to be encouraging at a time of rising hate crimes and during an administration that regularly fans fears of immigration.

And yet, around 25 percent of respondents espoused nativist attitudes, ranking being born in the United States or being Christian as essential to being American. For these respondents, even the most patriotic new immigrant is not a “real” American, and the “Americanness” of someone born and raised in the United States who is not Christian will always be in question.

Nativist understandings of who qualifies as an American have received renewed attention since the surprise election of Donald Trump in 2016, but questions about Americanness have always been at the heart of public life in the United States. The answers that have come to the fore in different historical moments have informed decisions about perhaps the most important public matter of all: whether to deny or extend the full rights of citizenship to particular people living in the United States.

In 1857, Chief Justice Roger Taney wrote in the infamous Dred Scott decision that African Americans were not “acknowledged as part of the people” who declared independence from Britain and ratified the Constitution, and were therefore not citizens of the United States. A century passed from 1868 ratification of the 14th Amendment, which nullified the Scott decision and established birthright citizenship, until the federal government tried to address the continuing exclusion of African Americans from the full rights and privileges of being American with the Civil Rights and Voting Rights acts.

Members of Native American communities did not become citizens of the United States until the Indian Citizenship Act of 1924. Full citizenship and voting rights didn’t arrive for all native people until 1948.

Conceptions of who can be a “real” American also have shaped immigration policy and reactions to new immigrants. The so-called “Know Nothings” of Abraham Lincoln’s day feared Catholic immigration as a threat to the dominant Protestant identity of the time. The Chinese Exclusion Act of 1882 prohibited Chinese immigrants from becoming citizens. Theories of Anglo-Saxon racial superiority, popular among some of our country’s most celebrated political leaders in the late 19th and early 20th centuries, led to claims that Irish, Southern and Eastern European immigrants were too different from the native-born population to become fully American.

Theodore Roosevelt and Woodrow Wilson were big fans of such theories.

Gender and race have also intersected in powerful ways regarding who could be a “real” American. After suffrage was extended to women in 1920, African American women continued to suffer from race-based exclusion from the full rights of citizenship. Until 1922, a female immigrant could not become a citizen apart from her husband, this at a time when race-based immigration rules were still very much in effect.

The details of debates about Americanness always reflect the specific circumstances of a historical moment playing out in the lives of particular communities. Today, Muslims in the United States, whether born here or having arrived as immigrants, find themselves at the center of such debates — with serious ramifications for their daily lives.

Muslims in the United States likely regularly encounter another person who views them as less than fully American. They experience this in countless ways: everyday harassment, assaults, opposition to mosque and graveyard construction, anti-Muslim legislation and policies, vandalism of mosques and Muslim-owned businesses, and of course a steady diet of anti-Muslim public discourse. These experiences are often heavily gendered, especially for women who choose to wear headscarves.

While only 25 percent of our survey respondents consider being Christian essential to “Americanness,” that’s a lot of people in the real world — and they are concentrated in one political party. This makes their voices overrepresented in our political debates and makes it impossible for some religious minorities to fully engage politically. A recent controversy in Tarrant County, Tex., illustrates this reality.

Last year, leaders of the county Republican Party named Shahid Shafi as vice chair. Shafi is a Muslim surgeon who arrived from Pakistan in 1990 to complete medical school and later became a citizen. He has been an active member of the party and is a member of the city council in Southlake, Tex.

Shortly after his appointment, a group of activists within the party began making incendiary charges and called for his removal. They produced no evidence for their claims other than the fact that he regularly attends services at his mosque.

County and state Republican leaders are reportedly horrified by efforts to remove Shafi, acknowledging that some within the party are in effect calling for a religious test for being Republican.

While Shafi’s case may be unusual, our polling shows that attitudes that marginalize naturalized citizens and religious minorities aren’t limited to the fringes of the Republican Party. Nearly half of people who identified as “strong Republicans” said that being born in the United States and being Christian were essential parts of being American. By contrast, only 25 percent and 22 percent of strong Democrats shared those respective points of view.

What should we make of the concentration of nativist views in one political party?

On the one hand, there is nothing surprising about it. Political parties exist to organize and channel ideas in the population for political debate, and nativist views have resonance among some voters. Both Europe and the United States in recent years have seen the emergence of parties catering to such voters, and it is possible that parties will continue to make nativist appeals as long as they believe they gain an advantage by doing so.

The challenge we see is that nativism is different from other issues that divide voters, such as the proper size and scope of government. Questioning someone’s Americanness is not about a difference in policy views — it is an attack on the very legitimacy of that person’s participation in public life. Such attacks, when used to prevent people from engaging in political activity, are deeply undemocratic.

Contemporary nativist views threaten the health of our two-party system by increasingly making one party inhospitable for anyone not fitting a nativist profile of Americanness. Many Republicans disavow nativist sentiments within the party. But this doesn’t necessarily cancel out their effects on the party as a whole. That’s a loss for voters who, like Shafi, seek to join a party sharing their views in favor of small government.

It’s also a loss for the country when one of its two major parties is unable to draw upon the full insights and talents of the entire American citizenry. The health of our democratic life depends on both political parties being truly open to everyone, capable of drawing on a diversity of experiences and voices to craft policies they believe will serve all Americans best.

Are the results of the Grinnell College poll encouraging? Yes and no. The fact that so many people associate being American with treating people equally and accepting people of different backgrounds is reason for optimism. At the same time, the poll points to just how much a minority of Americans can affect democratic life by creating inhospitable conditions for broad political participation and representation.

Perhaps the most important lesson is that the tension between these two points of view isn’t new. It is interwoven through our history and runs deep in our culture. Our hope is that these findings help us understand the particular ways these tensions are manifesting today, and thus the issues we need to confront to address our differences and remember the core values that can bind us together as Americans.