The existentialism we see today is rooted most prominently in the writings of Søren Kierkegaard, and as a consequence, it might be argued that modern existentialism started out as being fundamentally Christian in nature, only later diverging into other forms. It is thus important to understand Christian existentialism in order to understand existentialism at all.
A central question in Kierkegaard’s writings is how the individual human being can come to terms with their own existence, for it is that existence which is the most important thing in every person’s life. Unfortunately, we are as if adrift in a infinite sea of possible modes of living with no secure anchor that reason informs us will provide certainty and confidence.
This produces despair and anguish, but in the midst of our “metaphysical sickness” we will face a “crisis,” a crisis which reason and rationality cannot decide. We are forced to reach a decision anyway and to make a commitment, but only after making what Kierkegaard called a “leap of faith” — a leap that is preceded by an awareness of our own freedom and the fact that we might choose wrongly, but nevertheless we must make a choice if we are to truly live.
Those who have developed the Christian themes of Kierkegaard’s existentialism explicitly focus upon the idea that the leap of faith we make must be one which causes us to surrender ourselves totally to God rather than to insist on a continued reliance upon our own reason. It is, then, a focus upon the triumph of faith over philosophy or intellect.
We can see this perspective most clearly in the writings of Karl Barth, a Protestant theologian who was among the most faithful to Kierkegaard’s religious intentions and who can be looked upon as the starting point of explicitly Christian existentialism in the twentieth century. According to Barth, who repudiated the liberal theology of his youth on account of the experiences of World War I, the anguish and despair we experience in the midst of an existential crisis reveals to us the reality of the infinite God.
This is not the God of the philosophers or of rationalism, because Barth felt that rationalistic systems of understanding God and humanity had been invalidated by the destruction of the war, but the God of Abraham and Isaac and the God who spoke to the prophets of ancient Israel. Neither rational grounds for theology nor for understanding divine revelation should be sought after because they simply don’t exist. On this point Barth relied on Dostoyevsky as well as Kierkegaard, and from Dostoyevsky he drew the idea that life wasn’t nearly as predictable, orderly, and reliable as it appeared to be.