Secularism, Fundamentalism, or Catholicism? The Religious Composition of the United States to 2043

Abstract

We provide a cohort-component projection of the religious composition of the United States, considering differences in fertility, migration, intergenerational religious transmission, and switching among 11 ethnoreligious groups. If fertility and migration trends continue, Hispanic Catholics will experience rapid growth and expand from 10 to 18 percent of the American population between 2003 and 2043. Protestants are projected to decrease from 47 to 39 percent over the same period, while Catholicism emerges as the largest religion among the youngest age cohorts. Liberal Protestants decline relative to other groups due to low fertility and losses from religious switching. Immigration drives growth among Hindus and Muslims, while low fertility and a mature age structure causes Jewish decline. The low fertility of secular Americans and the religiosity of immigrants provide a countervailing force to secularization, causing the nonreligious population share to peak before 2043. © 2010 The Society for the Scientific Study of Religion.