As the nation celebrates the birth of the Rev. Martin Luther King Jr., the progressive left will again seize the moment to twist the story of black Americans’ struggle, to the detriment of those who suffered most in that struggle. They’ll put all the attention on the oppressive conditions faced by black freedom fighters—what white racists did to them—rather than on their own spirit in fighting to gain equal rights under the law. Instead of celebrating blacks’ achievements and the progress made toward delivering on America’s promissory note, the left will transport yesterday’s real injustices into today’s false social-justice...