evidence: The highest quality projections for religious communities are built on cohort-component projections—ones that use differential rates for each religion: age-specific fertility rates by religion, age structure in 5-year age-and-sex cohorts by religion, migration rates by religion, and mortality by religion. For instance, cohort-component projections are used for the projections at the Pew Research Center and at the Age and Cohort Change Project of the International Institute for Advanced Systems Analysis (IIASA). Unfortunately, this kind of detail is not yet available for many countries (half of censuses do not ask a question about religion). [...] Several factors account for the faster projected growth among Muslims than non-Muslims worldwide. Generally, Muslim populations tend to have higher fertility rates (more children per woman) than non-Muslim populations. In addition, a larger share of the Muslim population is in, or soon will enter, the prime childbearing years (ages 15–29). In the past few decades, improved health and economic conditions in Muslim-majority countries have led to greater-than-average declines in infant and child mortality rates, and life expectancy is rising even faster in Muslim-majority countries than in other less-developed countries.16 [...] Muslims continue to experience higher than average worldwide fertility rates, whereas Daoists are growing because of a religious resurgence in China.