Want a great article on the big-picture trends in global Christianity? Philip Jenkins has written a great intro. From the article:

In looking back over the enormous changes wrought by the twentieth century, Western observers may have missed the most dramatic revolution of all. While secular movements like communism, feminism, and environmentalism have gotten the lion's share of our attention, the explosive southward expansion of Christianity in Africa, Asia, and Latin America has barely registered on Western consciousness. Nor has the globalization of Christianity — and the enormous religious, political, and social consequences it portends — been properly understood.