Wednesday’s shooting of a U.S. congressman and others at a baseball practice in suburban Washington should serve as a reminder, if we still need one, that extremism can be found in all types of faces, backgrounds and ideas. The shooter, who was gunned down by quick-thinking Capitol police officers, was a 66-year-old Illinois man whose social media rants were critical of President Donald Trump and Republicans, and who had been an active supporter of Sen. Bernie Sanders’ presidential bid. Among his ties on Facebook was a group called “Terminate the Republican Party,” which he evidently attempted to do not at the ballot box but with a high-powered rifle.