Former Vice President Joe Biden endorsed Antifa in a video announcing his presidential bid Thursday, characterizing the group as “courageous” and saying it’s wrong to draw a moral equivalence between white nationalist groups and those opposing them. The violent methods of Antifa are well documented. The nebulous group often uses these violent means against peaceful conservative speakers, benign free speech advocates, and even journalists. In a retelling of the events at a 2017 white nationalist rally in Charlottesville, Va., Biden describes the white nationalists as having “crazed faces, illuminated by torches, veins bulging and baring the fangs of racism,” but...