The author, Andrew Walls (1928-2021), after patristics at Oxford and seven years teaching at universities in West Africa, spent the rest of his career in the Universities of Aberdeen and Edinburgh, teaching what came to be called World Christianity. The first chapter is a close reading of Acts and Eusebius, when Christianity was exclusively Jewish; the second brings Christianity to school with Hellenic culture, represented by Justin Martyr and Origen. Subsequent chapters take us through issues such as Christendom and “When World Christianity Fell Apart” to the world that we know, in which our Northern churches are emptying and millions crowd into the churches of Africa, Latin America, and the Pacific.