Who is Kierkegaard's target when he criticizes the philosophical "volatilization" of Christian faith? In this paper I will argue that Kierkegaard's early dispute with Immanuel Hermann Fichte in the spring of 1837 can be considered not only as the background of this critique, but also as the key to its proper understanding. After outlining the argument in Fichte's book The Idea of Personality and Individual Continuity (1834) in Section I, I will provide an interpretation of Kierkegaard's critical remarks on the younger Fichte in journal entry AA:22 in Section II. In Section III, I will then explore the relation between AA:22 and the journal entry CC:12, in which Kierkegaard for the first time expresses his critique of the philosophical "volatilization" of central Christian concepts. Here I hope to show that, according to Kierkegaard, the philosophical "volatilization" of Christian faith consists in the inappropriate usage of this concept within the philosophical realm, a misuse which results from conflating the realms and boundaries of philosophy and Christianity.