Advertisement Attorney General Merrick Garland and Homeland Security Secretary Alejandro Mayorkas testified before Congress that the greatest domestic threat facing the United States comes from racially and ethnically motivated violent extremists. Heavily promoted by the GOP, one third of adult Americans who responded to an AP/NORC poll now believe in some form of the racist Great Replacement Theory, an idea that nonwhite individuals are being brought to the United States to “replace” white voters. Get Weekend Reads from Ideas A weekly newsletter from the Boston Globe Ideas section, forged at the intersection of 'what if' and 'why not.' Enter Email...