Before 1914 most people in the West still believed in Enlightenment philosophies of progress, reason, and individual rights. As the century began, progress was a daily reality, apparent in the rising living standard, the taming of the city, the spread of political rights to women and workers, and the growth of state-supported social programs. Just as there were laws of science, many thinkers felt, there were laws of society that rational human beings could discover and wisely act on.

Even before the war, however, the particularly influential German philosopher Friedrich Nietzsche (NEE-chuh) (1844–1900) called such faith in reason into question. In the first of his Untimely Meditations (1873), he argued that ever since classical Athens, the West had overemphasized rationality and stifled the passions and animal instincts that drive human activity and true creativity. Nietzsche went on to ridicule Western society’s values. He believed that reason, democracy, progress, and respectability were outworn social and psychological constructs that suffocated self-realization and excellence. Rejecting religion, Nietzsche claimed that Christianity embodied a “slave morality” that glorified weakness, envy, and mediocrity. Little read during his lifetime, Nietzsche attracted growing attention in the early twentieth century.

The First World War accelerated the revolt against established philosophical certainties. Logical positivism, often associated with Austrian philosopher Ludwig Wittgenstein (VIHT-guhn-shtighn) (1889–1951), rejected most concerns of traditional philosophy — from God’s existence to the meaning of happiness — as nonsense and argued that life must be based on facts and observation. Others looked to existentialism for answers. Highly diverse and even contradictory, existential thinkers were loosely united in a search for moral values in an anxious and uncertain world. Often inspired by Nietzsche, they did not believe that a supreme being had established humanity’s fundamental nature and given life its meaning. In the words of the famous French existentialist Jean-Paul Sartre (ZHAWN-pawl SAHR-truh) (1905–1980), “Man’s existence precedes his essence. . . . To begin with he is nothing. He will not be anything until later, and then he will be what he makes of himself.”12

In contrast, the loss of faith in human reason and in continual progress led to a renewed interest in Christianity. After World War I several thinkers and theologians began to revitalize Christian fundamentals, stressing human beings’ sinful nature, the need for faith, and the mystery of God’s forgiveness. As a result, religion became much more relevant and meaningful than it had been before the war, and intellectuals increasingly turned to religion between about 1920 and 1950. Sometimes described as Christian existentialists because they shared the loneliness and despair of atheistic existentialists, these believers felt this shift was one meaningful answer to terror and anxiety. In the words of a famous Roman Catholic convert, English novelist Graham Greene, “One began to believe in heaven because one believed in hell.”13