On a sweltering afternoon in the summer of 2020, Amsa Burke climbed atop a cement picnic table and shared a truth she had long held close.

“Racism happens, even in a small Christian town,” she told dozens of demonstrators who had gathered to march for racial justice in Lynden, Wash., a predominantly white, rural community. “I have experienced it myself.”

A palpable tension hung in the air. National conversations about racism were at a boil, in the wake of George Floyd’s murder on May 25. Ms. Burke, then 17 and heading into her senior year at the public high school, saw her fellow marchers around her. Many were white classmates, others were supporters from near and far who believed this polite town needed to confront its views on race.

But Ms. Burke also saw a fired-up crowd of counterprotesters. They were angry. They were armed. She felt they exuded rage as they waved Trump signs and American flags. As she spoke, she could hear them loudly singing a hymn weighted with historical resonance: “Amazing Grace.”

It felt like a weapon. The hymn, which was written by an abolitionist and was significant in Black history and the civil rights movement, was being used in that moment to overpower the voice of a young Black woman.