How the West Really Lost God: A New Theory of Secularisation. By Mary Ebertsadt. Templeton Press; 257 pages; $24.95. THE family that prays together, stays together. That folksy motto, which was first used in a Catholic campaign to encourage households to say the rosary, became popular in America after the second world war when the nation underwent a temporary upturn in both fecundity and piety. The two phenomena were intimately connected, thinks Mary Eberstadt of the Ethics and Public Policy Centre, a think-tank based in Washington, DC. Her short, elegantly written book repeatedly shows that strong families help to keep religious practice alive, and that too many people see a causal connection running exclusively in the opposite direction. In other words, it is widely assumed that people form large families because they hold traditional beliefs, and that when they abandon those beliefs, they stop creating those families. For Ms Eberstadt, the link between robust families and resilient faith is reminiscent of bonds forming a double helix: dynamic, self-reinforcing and flowing endlessly in both directions. And if there is one trend for her which has primacy, it seems to be the influence of the family on everything else. Where it is strong, people continue to pray, publicly and privately; where ties of kin disintegrate, so does religion. As anyone who has observed a devout, traditionally organised community will affirm, family and faith reinforce one another in many ways. In such a world the parish or mosque or synagogue shares with the extended family the task of socialising children, in whose young minds the two sorts of obligation (to family and faith) become interchangeable. In such communities invisible bonds link past and future generations. Passing on time-honoured beliefs and rituals feels like an obligation so deep that it hardly needs verbalising. Even if their own metaphysical beliefs have grown hazy, parents may still feel a deep compulsion to impart to their children whatever they learned in their youth. When that compulsion wanes, belief may well disappear. All that is worth saying, but there is another side to the story, which this book does not touch on. True, family bonds sustain religion where it might otherwise attenuate. But really powerful spiritual renewals (from the birth of new faiths, to prophetic revivals within old ones) often take place in scandalous defiance of family ties. That applies to the birth of Christianity itself. The New Testament contains powerful warnings that in certain circumstances, loyalty to Jesus Christ must supersede the bonds of kin. Up to modern times the influence of powerful monastic movements, whose participants sever conventional family ties and form new ones, has been a decisive feature of many religious cultures, from Orthodox Christianity to Buddhism. Secular ideologies, such as Leninism or Peronism, for example, also go through fluctuations. Phases of blazing passion, where all conventional arrangements are challenged, can give way to deep, protective conservatism once a new order has been established. A similar alternation can be seen in the history of the world's great religions: prophecy and social turmoil followed by a pickling in the aspic of social and cultural tradition. As Ms Eberstadt understands well, family solidarity and moral pressure can enable a great religious tradition to survive many travails. But in the long run, a religion may not survive unless it is also open, from time to time, to bursts of uncompromising fervour, the sort that invites people to cast every other consideration aside, including their own kin.