Trump's tweets telling minority congresswomen to “go back” to their countries follows a history of racism and nativism. Voters will decide if this is effective. (Video: The Washington Post)

President Trump has forced us all to take a position on what kind of America this is going to be — in essence, to define again what American “nationalism” means. Is it a white Christian nationalism (or if you’re Jewish and think you can wriggle yourself inside the Trumpian nationalist tent, you can call it Judeo-Christian), in which immigrants of color or other religions are not really Americans and can be told by the president to “go back” to their ancestral lands? Or is it the universalist nationalism of the Declaration of Independence, based on the liberal Enlightenment principles of equality before the law, the inviolable rights of the individual against the state and the conviction that all citizens — regardless of religion, ethnicity or ancestral roots and the timing of their arrival — are equally American?

This is hardly the first time that Americans have been presented with this question, needless to say, and they have often answered equivocally. The popular willingness to denounce and even persecute the “hyphenated” Americans of German and Irish descent during and after World War I, a frenzy spurred by leaders of both political parties; the imprisonment of U.S. citizens of Japanese descent during World War II, upheld by the Supreme Court; and of course the unending horrific treatment of African Americans — these are more than sad episodes in our history. They are as much a part of who we are as the civil rights movement and other triumphs of individual liberties. White nationalism was never just a fringe phenomenon, and it isn’t today. The South was a bastion of the white-nationalist idea for almost two centuries and with support in the last half of the 20th century from conservative thinkers such as Russell Kirk and William F. Buckley Jr. Today, the American conservative movement proudly nurtures a new nationalism, whose intellectual authors openly call on Americans to reject the universal liberal principles of the Declaration of Independence in favor of a nationhood grounded in religion and culture. It is a growth industry.

This nationalism is antithetical to the American experiment. The Founding Fathers, though white, Christian men, explicitly rejected establishing the new republic on a religious and ethnic foundation. They did not share a Burkean belief that the rights they enshrined in the Declaration derived from their Anglo-Saxon Protestant heritage, accreted over the centuries. As Alexander Hamilton put it, the “sacred rights of mankind” were not to be found among “parchments or musty records” but were “written, as with a sunbeam . . . by the hand of the divinity itself.” In the Declaration of Independence, which Abraham Lincoln recognized as the quintessential statement of American nationalism, there is not a word about culture, color or Christianity.

Yet the fight to define our nationalism has continued ever since. And that is what’s at stake in the current confrontation between the president and “the Squad.”

As always in such fights, the battle is not being fought on the clear and solid ground we’d all prefer. Trump himself deliberately picked this murky ground. He knows that a great number of Americans in both parties have little sympathy for the Squad, and for all kinds of reasons, ranging from simple racism, Islamophobia and misogyny, to genuine policy disagreements, to unhappiness with the bigotry and insensitivity that members of the Squad have themselves sometimes displayed. Almost everyone has a reason to temper their support. Professional Republicans are silent because they fear their voters; professional Democrats are still angry at the Squad for challenging House Speaker Nancy Pelosi (D-Calif.). Many are inclined to declare a pox on both their houses — they deserve each other.

Unfortunately, we don’t have the luxury of equivocation. Trump has given us a binary choice: Either stand with American principles, which in this case means standing in defense of the Squad, or equivocate, which means standing with Trump and white nationalism. It doesn’t matter how you feel about Reps. Alexandria Ocasio-Cortez (D-N.Y.) and Ilhan Omar (D-Minn.). The truth is, they have done nothing and said nothing about the United States or about an ally (in this case, Israel) that has not been done or said thousands of times. When politicians were denouncing “hyphenated” Americans during World War I, German and Irish Americans were not only denouncing their government. Some were actively working for the German government, engaging in sabotage and espionage, often supported by funds paid through the German Embassy in Washington. Yet even that did not justify a national assault on “hyphenated” Americans.

Our nation won’t be undermined by anything the Squad has said or done. It will be undermined if we don’t fight back against this assault on our universal principles. Disagree with the Squad, refute them, argue with them, vote against them. But also defend them, as the founders intended. The essence of our nation is at stake.

Read more:

Max Boot: I may not agree with AOC’s squad, but they are better Americans than Trump

Henry Olsen: Yes, Trump’s tweets are offensive. But there’s one big reason Republicans still stand by him.

Eugene Robinson: Republicans embrace Trump’s racism. Blame them as much as him.

Richard Cohen: Republicans must acknowledge that their party has been taken over by a racist

George Conway: Trump is a racist president

The Post’s View: Trump’s racist tweets are one of the lowest moments of his presidency

Dana Milbank: The racism stops when Trump goes back to the place from which he came