FADING FAITH chronicles the decline of religion in modern democracies and predicts that America is traveling this path to secularism. A profound transition is occurring, barely noticed. Slowly, imperceptibly, supernatural religion is shriveling. Pope Benedict XVI laments that ''Europe has developed a culture that, in a manner unknown before now to humanity, excludes God from the public conscience.'' In Denmark and Sweden, fewer than 5 percent of adults are in church on a typical Sunday. Although over half of British children attended Sunday school in 1900, by 2000 the rate was down to 4 percent. In America, despite the superficial success of evangelical groups, surveys since 1990 have shown that the godless fraction of Americans had doubled from one-tenth to one-fifth of the adult population. Around 45 million Americans live apart from churchgoing. A 2012 Gallup poll found that one-third of U.S. adults now say religion is inconsequential to them.