Ever since the Enlightenment, deep thinkers have claimed that modernity would drive out religion, probably by the end of the 20th Century. In April, a Newsweek magazine cover announced "The Decline and Fall of Christian America," while God Is Back, published that same week, is subtitled How the Global Revival of Faith Is Changing the World. The contrast illustrates the worldwide tension between secularism in modern political life and the growing prevalence of religious belief. Free-market thinking has some people shopping between denominations. Some traditionalists threatened by the secular world go to extremes. This evergreen program, originally aired in April, is especially interesting on Christmas Day. Do religions compete for believers? Which one is likely to win? Why is Osama bin Laden's al Qaeda such a "Modern" phenomenon?