From The Economist‘s very worthwhile 18-page special report on religion and public life:
In global terms the most remarkable religious success story of the past century has been the least intellectual (and most emotive) religion of all. Pentecostalism was founded only 100 years ago in a scruffy part of Los Angeles by a one-eyed black preacher, convinced that God would send a new Pentecost if only people would pray hard enough. There are now at least 400 million revivalists around the world. Their beliefs are not for the faint-hearted. According to a study of ten countries by the Pew Forum on Religion & Public Life, most adherents have witnessed divine healing, received a “direct revelation from God” or seen exorcisms.