For Kierkegaard Christian faith is not a matter of regurgitating church dogma. It is a matter of individual subjective passion, which cannot be mediated by the clergy or by human artefacts. Faith is the most important task to be achieved by a human being, because only on the basis of faith does an individual have a chance to become a true self. This self is the life-work which God judges for eternity.
The individual is thereby subject to an enormous burden of responsibility, for upon h/er existential choices hangs h/er eternal salvation or damnation. Anxiety or dread (Angest) is the presentiment of this terrible responsibility when the individual stands at the threshold of momentous existential choice. Anxiety is a two-sided emotion: on one side is the dread burden of choosing for eternity; on the other side is the exhilaration of freedom in choosing oneself. Choice occurs in the instant (Øjeblikket), which is the point at which time and eternity intersect — for the individual creates through temporal choice a self which will be judged for eternity.
But the choice of faith is not made once and for all. It is essential that faith be constantly renewed by means of repeated avowals of faith. One’s very selfhood depends upon this repetition, for according to Anti-Climacus, the self “is a relation which relates itself to itself” (The Sickness Unto Death). But unless this self acknowledges a “power which constituted it,” it falls into a despair which undoes its selfhood. Therefore, in order to maintain itself as a relation which relates itself to itself, the self must constantly renew its faith in “the power which posited it.” There is no mediation between the individual self and God by priest or by logical system (contra Catholicism and Hegelianism respectively). There is only the individual’s own repetition of faith. This repetition of faith is the way the self relates itself to itself and to the power which constituted it, i.e. the repetition of faith is the self.
Christian dogma, according to Kierkegaard, embodies paradoxes which are offensive to reason. The central paradox is the assertion that the eternal, infinite, transcendent God simultaneously became incarnated as a temporal, finite, human being (Jesus). There are two possible attitudes we can adopt to this assertion, viz. we can have faith, or we can take offense. What we cannot do, according to Kierkegaard, is believe by virtue of reason. If we choose faith we must suspend our reason in order to believe in something higher than reason. In fact we must believe by virtue of the absurd.