In the aftermath of the horrific Newtown, Conn., school massacre, Americans from all parts of the political spectrum agree that we need to pay more attention to mental health issues. Public death threats and incitements to violence must be taken seriously. The incendiary witch hunt against law-abiding, peaceful gun owners is neither noble nor effective. It’s just plain insane. Over the past week, I’ve witnessed a disturbing outbreak of off-the-rails hatred toward gun owners and Second Amendment groups. Whatever your views on guns, we can all agree: The Newtown gunman was a monster who slaughtered his own mother, five heroic...