Scholars of contemporary Christianity rightly stress the enormous worldwide upsurge of Pentecostalism. In numerical terms at least, it represents the greatest success story in modern religion. A new movement just a century ago, Pentecostalism today claims hundreds of millions of adherents.

Much of that story involves demographic change. As populations have swelled in Africa, Asia, and Latin America, many millions have been uprooted from traditional villages.

Most have moved to new megacities in their own countries, but other former rural dwellers have journeyed to cities in the Global North. In the challenging situations they face in their new homes, migrants naturally gravitate to those religious groups that offer them the means of survival. They find there opportunities for fellowship and community, but also the basic necessities of welfare, education, and health that the state cannot provide. Commonly, it is the Pentecostal and charismatic churches that are best organized to supply these needs, and in turn they benefit most from the repeated infusions of the uprooted.