Christianity is the largest faith in a world of thriving religions. It’s hard sometimes to feel that since the mental picture that grips most Westerners, including many Christians, is one of a dying faith in a disenchanted secular universe in which God is not so much dead as retired on a modest pension. Reality is very different. In 2015 the four largest (conventional) world religions were in descending order Christianity (31.2 per cent of the global population), Islam (24.1 per cent), Hinduism (16 per cent), and Buddhism (7 per cent). If we admit “without religion” as a category, that comes in third today with 16 per cent, a shade ahead of “without religion”.