In a very recessed and implicit fashion, Karl Barth's theology, as explicated in works like "Church Dogmatics", follows Soren Kierkegaard's "Stages on Life's Way". "A Humble Courage" traces the parallels between Barth's theology and Kierkegaard's philosophy.
While historical generalizations are notoriously hazardous, we may say that one of the issues that precipitated the Protestant Reformation was the role of mediation in relation to faith. Prior to the Reformation, the believer’s salvation was mediated, at least in the minds of the Reformers, by an elaborate hierarchy of priests, bishops, and popes in this world, and a no less elaborate hierarchy of confessors, saints, virgins, and martyrs in the next. The believer’s interpretation of Scripture was subject to the same mediation. The consequent...