David Horowitz has always been a writer whose work I've appreciated since his compelling political biography, Radical Son, which related the author's break from his communist upbringing after Black Panther associates murdered his bookkeeper friend Betty Van Patter. But brevity and crisp linkage of multiple intellectual threads were never characteristic of Horowitz's brilliant, often voluminous, exposés of leftist thought and practice. By contrast, Dark Agenda is a concise, chilling book brimming with evidence that links numerous cultural depredations to one overriding theme: The left's attack on Christian America's founding in the name of "cultural Marxism." "Christian America" is the novel...