When pipe bombs turned up in the mail of Hillary Clinton and other prominent Democrats this week, the first recipient — billionaire investor and liberal philanthropist George Soros — quickly fell out of the headlines. But there’s no chance his many critics and enemies have forgotten him. White nationalists and others on the political fringes have long cast Soros as the supposed leader of a globalist Jewish plot to undermine white Christian civilization. Now, President Donald Trump, Hungarian Prime Minister Viktor Orban and other political leaders have brought the vilification of Soros into the mainstream. This year, Soros has been...