The Church Solutions Factbook08 has an interesting article about the next 1000 years of Christianity, contributed by the Fermi Project. One prediction is that the centre of Christianity will shift west. In its first 300 years, the centre of Christianity shifted from Jerusalem to Armenia. In the next 200 years it moved west to Greece and Rome. Over the next 500 years it moved further west into Europe. Over the next 1000 years it moved further west into North and South America. The centre of Christianity is still moving west, with the rapid growth rates in Korea (although the number of Christians in Korea started to decline last year) and China, so that by the year 2500 the world might identify Christianity as primarily an Asian thing.
Another prediction is that the varieties of Christianity will continue to increase. In 1800 there were 500 Christian denominations; by 2007 there were 40,000, and by the next century there may be as many as 260,000. Churches at the margins of Christian denominations are likely to continue to be those which grow fastest – the Mormons and the Amish are growing rapidly at the moment. The largest denomination in 1000 years’ time will almost certainly be one which does not exist today.
Another prediction is that almost all of the challenges faced by Christianity over the next 1000 years will be driven by new technologies. Another prediction is that as the influence of Islam continues to grow in Europe, Christians and Muslims may become conservative political allies in much the same way as Christians and Jews are today.