Over time, Christianity ceased to be a comprehensive, world-changing religion. “[W]here religion still survives in the modern world, no matter how passionate or ‘committed’ the individual may be, it amounts to little more than a private preference, a spare-time hobby, a leisure pursuit.”[8] Theodore Roszak used an apt phrase to describe much of modern-day Christendom: “Socially irrelevant, even if privately engaging.”[9]
The advance of Islam in our day has taken place because of Christianity’s privatized religion and the advance of secularism. Religion, like nature, abhors a vacuum. G.K. Chesterton observed that when people cease to believe in God, they do not end up believing in nothing; they end up believing in anything, no matter how absurd.