In his book "Sickness Unto Death"
Kierkegaard defines faith as opposed to sin and as the complete overcoming of
desperation. Faith for Kierkegaard is not a matter of rational debate and it
does not have to do with any facts. Accepting the things written in the bible
as such is not faith in Kierkegaard's eyes but just a matter of indoctrination.
From another direction, faith for Kierkegaard cannot be inspired by historical
research or philosophy. Faith is not rational for Kierkegaard who opposes it to
the mental and rational and identifies it with wonder and Paradox (see Fear and Trembling for examples). Faith for Kierkegaard inspires the existential
revolution of the whole soul which transcends above everyday life in which most
humans dwell. See also: Leap of faith.