In the 1860's, following the revelations of geology and evolution, Matthew Arnold imagined the 'sea of Faith' as a tide: "But now I only hear its melancholy, long, withdrawing roar, retreating... down the vast edges drear, and naked shingles of the world." (Dover Beach) Now, in the 21st century that retreat, in the West, has reached the point that half the population has abandoned Christianity, the rituals and creeds of which have ceased to have meaning in a Post-Enlightenment age. Yet, in Western Europe, Christianity, at its best, defined our civilisation, with its accompanying morality, art, music and architecture, inspiring such movements as the anti-slavery campaign, the compassionate treatment of the insane, and a myriad of charities for the sick and deprived. This morality came directly from the teaching of Jesus of Nazareth, encapsulated in the so-called Sermon on the Mount.