This paper seeks to explain the continuing strength of religious values and the vitality of spiritual life in the United States compared with many other rich nations. Part I documents these patterns using a wealth of survey evidence and Part II then considers three alternative explanations of these differences. Religious market theory postulates that intense competition between rival denominations generates a ferment of activity explaining the vitality of churchgoing. Functionalist explanations focus on the shrinking social role of religious institutions, following the growth of the welfare state and the public sector. We compare evidence supporting these accounts with the theory of secure secularization, based on societal modernization, human development, and economic inequality, that lies at the heart of this study. This study draws on a massive base of new evidence generated by the four waves of the World Values Survey executed from 1981 to 2001. This includes representative national surveys in almost eighty societies, covering all of the world?s major faiths. We also examine other evidence concerning religiosity from multiple sources, including Gallup International polls, the International Social Survey Program, and Eurobarometer surveys. The conclusions consider the broader implications of the findings for the role of faith in politics, for patterns of secularization worldwide, and for growing cultural divisions between Europe and the United States.