This is an amazing book. An heir apparent to Philip Jenkin's "The Next Christendom," Sanneh focuses mainly on Africa, migration, and how independent, indigenous communities of faith in the majority world are adapting the faith and making it the normative expression of Christianity. Sanneh uses the Jewish-Gentile conflict from Acts 15 to serve as a template with which to discuss the growth of Christianity around the world and its accompanying conflicts over cultural expressions and contextualization. Great place to start to learn about World Christianity and the West's ever shrinking dominance.