Last year Mayor Bill de Blasio announced that for the first time New York City schools would be closed for two Muslim holidays: Eid al-Fitr, marking the end of a month of fasting called Ramadan, and Eid al-Adha, which many of the faithful commemorate with a pilgrimage to Mecca. The UFT strongly supported the policy change. Nearly 1 million Muslims live in the city, and about 10 percent of the students enrolled in public schools are Muslim.

Our public schools, which have long absorbed successive waves of immigration, are a powerful symbol of how generations of immigrants have become Americans, inducted into the civic life of the city and the nation. David Dinkins famously championed the city’s diversity by calling it “a gorgeous mosaic.”

That’s an important image to keep in mind in this season of Donald Trump. His presidential campaign has given voice to an ugly and intolerant strain in American life that periodically rears its head. At one time, it was Irish Catholics who were vilified; at another time, Chinese laborers. It’s a shameful mark on our history that the United States shut the door on Jews fleeing the Holocaust and interned Japanese Americans during World War II. And today, even as the presidency of Barack Obama draws to a close after eight years, no one can say that we have fully reckoned with the deep and persistent racial divide in our country.

A countervailing feature of American life is the ongoing efforts by many to heal these historical wounds; it is evident in the UFT’s long commitment to social justice in the classroom and beyond. It’s something to hold on to when the GOP candidates for president all agree that no Syrians fleeing a horrific war should find refuge in the United States and Trump calls Mexicans “rapists,” promises to deport 11 million undocumented people and vows to bar Muslims from entering the country.

As educators and unionists, we are charged with reminding our students and ourselves that even in these frightening times — after the terror attacks in Paris, San Bernardino and elsewhere — we cannot give in to bias and fear-mongering. It will not keep us safe. Instead, it wrecks the best part of who we are.