In 2011, the scholar Eric Kauffman wrote the book Shall the Religious Inherit the Earth?: Demography and Politics in the Twenty-First Century and he published the academic paper Shall the Religious Inherit the Earth?: Demography and Politics in the Twenty-First Century which argued that secularization would peak in the developed world by 2050.Overall, the picture suggests that the U.S. will continue to secularize in the coming decades. However, a combination of religious immigration, immigrant religious retention, slowing religious decline due to a rising prevalence of believers among the affiliated, and higher native religious birth rates will result in a plateauing of secularizing trends by mid-century.
We find considerable stability of religious groups over time, but there are some important shifts. Hispanic Catholics experience the strongest growth rates to 2043. Immigration, high fertility, and a young age structure will enable this group to expand from 10 to 18 percent of the American population between 2003 and 2043, despite a net loss of communicants to secularism and Protestantism. This will power the growth of Catholics as a whole, who will surpass Protestants by mid century within the nation’s youngest age groups. This represents a historic moment for a country settled by anti-Catholic Puritans, whose Revolution was motivated in part by a desire to spread dissenting Protestantism and whose populationon the eve of revolution was 98 percent Protestant (Huntington 2004; Kaufmann 2004). Another important development concerns the growth of the Muslim population and decline of the Jews. High Muslim fertility and a young Muslim age structure contrasts with low Jewish childbearing levels and a mature Jewish age structure. Barring an unforeseen shift in the religious composition and size of the immigrant flow, Muslims will surpass Jews in the population by 2023 and in the electorate by 2028. This could have profound effects on the course of American foreign policy. Within the non-Hispanic white population, we expect to see continued Liberal Protestant decline due to low fertility and a net loss in exchanges with other groups. White Catholics will also lose due to a net outflow of converts. Fundamentalist and Moderate Protestant denominations will hold their own within the white population, but will decline overall as the white share of the population falls.The finding that Protestant fundamentalism may decline in relative terms over the medium term contrasts with a prevailing view that envisions the continued growth of “strong religion” (Stark and Iannaccone 1994a). This is the result of an older age structure, which increases loss through mortality, and immigration, which reduces the size of all predominantly white denominations — all of which are poorly represented in the immigration flow. Fundamentalists’ relatively high fertility and net surplus from the religious marketplace is not sufficient to counteract the effects of immigration. Obviously, this could change if significant immigration begins to arrive from more Pentecostalist source countries such as Guatemala or parts of sub-Saharan Africa.
Our work also sheds light on the religious restructuring paradigm, though we do not find a clear victor between secularism and fundamentalism. The secular population will grow substantially in the decades ahead because it has a young age structure and more people leave religion than enter it. The sharpest gains for secularism will be within the white population, where seculars will surpass fundamentalists by 2030. On the other hand, there are important demographic limits to secularism, demonstrating the power of religious demography. The relatively low fertility of secular Americans and the religiosity of the immigrant inflow provide a countervailing force that will cause the secularization process within the total population to plateau before 2043. This represents an important theoretical point in that demography permits society to become more religious even as individuals tend to become less religious over time."