In the initial media churn, they were nearly missed. But a small band of Hebrew Israelites, members of a historic but little-known American religious movement, may actually be at the center of a roiling controversy that has gripped the nation in recent days. It began with a now-viral video clip, filmed Friday at the Lincoln Memorial in Washington, in which high school students from a Catholic school in Kentucky appeared to be in a faceoff with a Native American elder, who was beating on a drum. The boys, some wearing red hats with President Trump’s 2016 campaign slogan, appeared in...