Kierkegaard’s debt to Kant is at once obscure and enormous. There are only 17 explicit references to Kant in the works published by Kierkegaard during his lifetime. This compares with over 300 references to Hegel, 55 to Aristotle and over 90 to Kierkegaard’s Danish philosophical contemporary Hans Lassen Martensen. But despite this paucity of overt references, Kant is a major presence in some of Kierkegaard’s most important pseudonymous books, including Either/Or, Fear and Trembling, Philosophical Fragments and the Postscript. Kant’s thought also figures predominantly in two of Kierkegaard’s most important religious discourses, Works of Love and Purity of Heart. In what follows, I will suggest that although Kierkegaard clearly rejected some aspects of Kant’s rationalist philosophy, he more often used it as the philosophical platform on which to construct his own unique religious authorship.