In order to grasp the current situation of world Christianity concretely, consider what went on last Sunday. More Roman Catholics attended church in the Philippines than in any single country of Europe. In China, where in 1970 there were no legally functioning churches at all, more believers probably gathered for worship than in all of so-called "Christian Europe." And in Europe (as reported by Philip Jenkins) the church with the largest attendance last Sunday was in Kiev, and it is a church of Nigerian Pentecostals. Last Sunday, more Anglicans attended church in each of Kenya, South Africa, Tanzania, and Uganda than did Anglicans in Britain and Canada and Episcopalians in the U.S. combined. And several times more Anglicans attended church in Nigeria than in these other African countries. In Korea, where a century ago there existed only a bare handful of Christian believers, more people attended the Yoido Full Gospel Church in Seoul than all of the churches in significant American denominations like the Christian Reformed Church. In the United States, Roman Catholic mass was said in more languages than ever in American history. Last Sunday many of the churches with the largest congregations in England and France were filled with African or Caribbean faces. As a final indication of global trends, as of 1999 the largest chapter of the Jesuits was in India, and not as in the United States as had been the case for many decades before.
In a word, the world Christian situation is not what it was when your grandparents were born, or even when you were born.
Mark Noll, Faith and Conflict : The Global Rise of Christianity