An outsider’s look inside groups and gripes

Arthur Goldwag writes entertaining and erudite encyclopedias. His “’Isms and ’Ologies’’ defines hundreds of movements and religions that have shaped the world. He moves to more secular territory with his new book, “Cults, Conspiracies, & Secret Societies: The Straight Scoop on Freemasons, the Illuminati, Skull & Bones, Black Helicopters, the New World Order, and Many, Many More’’ (Vintage, paperback, $16), out this week. Goldwag is a colorful writer who makes good use of his material as he aims to explain, rather than debunk or expose, a fascinating diversity of beliefs.