• Søren Kierkegaard: religious beliefs are beliefs, not objective bits of knowledge.  The confrontation with, and anguish (angst) over, the ambiguity of human existence--what is its point if one is going to die anyway?--raises the prospect of the meaninglessness of one's existence.  Since no convincing arguments can be given to justify existence itself, the only proper (i.e., authentic) response is unconditioned faith, belief that there is a God who has promised us his salvation.

Abraham is the embodiment of the religious mentality.  He is not great because he is willing to sacrifice what he loves most but because he acts not knowing (in fear and trembling) whether he is right but nonetheless believes that this is what God asks of him.  Indeed, humanly speaking, he is insane because his act is unintelligible and even contradicts what God has told him to expect as the father of a great nation: he acted "by virtue of the absurd."  That is, he took responsibility for his action, affirming his power rather than engaging in (Freudian) resignation.

[The three enemies of authentic existence and faith are: (1) established Christianity (i.e., doing what the Church says is right); (2) middle-class, bourgeois culture (i.e., doing what society says is right); and (3) the dominant philosophy of the day (i.e., Hegelianism, in which truth is objective, rational, totalizing).  The aesthetic life lies in doing what seems or "feels" right according to society because it is what we have been taught; the moral life consists in doing what can be rationally justified (philosophically); only the religious life entails acting on faith in doing this or that particular action.]

Truth is subjectivity.  Rationality and knowledge are based on the premise that truth is objective, impersonal, a relationship between a belief and the world.  But the truth about human existence is not something about which we are simply intellectually curious but is rather something about which we care deeply.  Our caring about it determines it as something different from other things; that is, what it is is depends on how we feel about it.  Our existence and salvation are meaningful not because they correspond to some objective fact but because our interest in them is unconditioned and passionate, without any inner reservations or doubt.  This entails:

The leap of faith: there is ultimately no justification for the belief in eternal life and God's existence; the gap between the finiteness of our comprehension and the infinity of the justification is incommensurable.  Only a leap of faith can surmount the gap.  Religious belief must be just that--a belief for which one cannot give rational justification.  Knowledge of moral directives is rationally possible on a universal level but not on the personal level, and doing something because it is the socially acceptable (or aesthetic) thing to do involves no faith at all.  Moral knowledge is general, faith in salvation is particular.  The leap of faith is not irrational as much as beyond rationality.

Objection: But how is fanaticism different from religious faith?