This book provides a history of unparalleled scope that charts the global transformation of Christianity during an age of profound political and cultural change. It shows how one of the world's great religions changed during an age of world wars, genocide, nationalism, decolonization, and powerful ideological currents, many of them hostile to Christianity. Written by a leading scholar of world Christianity, the book traces how Christianity evolved from a religion defined by the culture and politics of Europe to the expanding polycentric and multicultural faith it is today--one whose growing popular support is strongest in sub-Saharan Africa, Latin America, China, and other parts of Asia. Transnational in scope and drawing on the latest scholarship, it demonstrates how Christianity has had less to fear from the onslaughts of secularism than from the readiness of Christians themselves to accommodate their faith to ideologies that privilege racial identity or radical individualism.