I read this recently in Tim Keller’s book King’s Cross. This is fascinating.

In an interview Andrew Walls, a distinguished historian of world Christianity, noted that wherever the other great world religions began, that is still their center today. Islam started in Arabia, at Mecca, and the Middle East is still the center of Islam today. Buddhism started in the Far East, and that’s still the center of Buddhism. So too with Hinduism–it began in India and it is still predominantly an Indian religion. Christianity is the exception; Christianity’s center is always moving, always on a pilgrimage.

Walls hinted that when Christianity is in a place of power and wealth for a long period, the radical message of sin and grace and the cross can become muted or even lost. Then Christianity starts to transmute into a nice, safe religion, one that’s for respectable people who try to be good. And eventually it becomes virtually dormant in those places and the center moves somewhere else.