RONNELLE ADAMS came out to his mother twice, first about his homosexuality, then about his atheism. “My mother is very devout,” said Mr. Adams, 30, a Washington resident who has published an atheist children’s book, “Aching and Praying,” but who in high school considered becoming a Baptist preacher. “She started telling me her issues with homosexuality, which were, of course, Biblical,” he said. “ ‘I just don’t care what the Bible says about that,’ I told her, and she asked why. ‘I don’t believe that stuff anymore.’ It got silent. She was distraught. She told me she was more bothered...