The places where Christianity is spreading and mutating are also places where the population levels are rising quickly�and, if Jenkins's predictions hold true�will continue to rise throughout the next century. The center of gravity of the Christian world has shifted from Europe and the United States to the Southern Hemisphere and, Jenkins believes, it will never shift back. So when American Catholics, for instance, talk about the necessity and the inevitability of reforms (reforms that Southern Catholics would most likely not condone), they do so without fully realizing that their views on the subject are becoming increasingly irrelevant, because the demographic future of their Church lies elsewhere.
I think the article misfires, however, in stating that this will lead to conflict with Islam. Islam is not expanding as rapidly in South America compared to Christianity, but rather is making far more inroads in the West. For example, the rise of Hispanic muslims in America. I agree that Africa is a potential source for converts to both religions, but religion is the least likely source of conflict there, compared to race and tribe (and anyway, AIDS is a far more immediate problem in Africa than religion). I also don't buy the argument that India is equal ground for conversion by Christians and Muslims - Christianity has an impressive, but fractionally insignificant, presence. The primary conversions there will be to Islam. Even in those places where there will be competition for converts (like the Philippines), I dont see any reason why this would necessarily lead to conflict. Muslims and Christians are for the most part compatible and apart from places like the Middle East (where the tension is imposed for political and strategic reasons) tend to live together in peace.
UPDATE: Zachary Latif comments, saying that Christianity is indeed a force to be reckoned with in India. I agree for the most part but he hasnt really taken certain Muslim comunities like the Bohras (my comunity) and the Nizaris into account in his analysis. Part of our difference in outlook is due to his ethnic origins from outside India (his ancestry hails from Zoroastrian Persia) whereas mine in indigineous to India, namely converts to Islam from the lower Hindu castes. My ancestors converted despite the appeal of Christianity and is why I still feel that Islam remains the primary attraction to converts rather than Christianity - comunities like mine offer a vibrant economic and egalitarian social escape from the caste system. That may not be true of some muslim communities in India, but its very true of mine.