This chapter uses standard demographic methods to project changes in the size of eight major religious groups from 2010-2050. The groups, presented in descending order of their 2010 size, are: Christians, Muslims, the religiously unaffiliated, Hindus, Buddhists, adherents of folk or traditional religions, members of “other religions” (consolidated into a single group) and Jews.

Each section begins with an overview of projected population trends for a particular religious group, including its expected annual growth rate in the coming decades. The sections also look at projected changes in the regional distribution of each group, as well as changes in the 10 countries with the largest populations of each group from 2010 to 2050. Finally, the sections examine the demographic factors behind the expected changes: fertility, life expectancy, age structure, religious switching and migration.