HBO caused a major stir on social media with Sunday night’s broadcast of “Going Clear: Scientology and the Prison of Belief,” a blistering documentary about the Church of Scientology and its celebrity devotees. People Magazine published a teaser for the film Sunday, which was first screened in January at the Sundance Film Festival. Sensational in content but not in tone, Going Clear has been making headlines since its first screening at Sundance in January. It has also upset that secretive, combative and often embattled Church, which in a lengthy statement attacked the film as “insidious religious persecution by bullies toting...