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.

Even before the war, however, the 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 Western civilization overemphasized rationality and stifled the passions and animal instincts that drive human activity and true creativity. Nietzsche 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 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 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.”2

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, 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 that religion was one meaningful answer to terror and anxiety.