This is a study about the relationship between the ethical sphere and Christianity in Kierkegaard's thought. Against the tendency among Kierkegaard scholars to emphasize the continuity between the ethical sphere and Christianity, I tried to show through this study that in Kierkegaard's writings there was a very strong emphasis on the discontinuity between these two spheres. I started by asking whether there is a difference and discontinuity between "rationalistic ethics" (the ethics of the person who is in the ethical sphere) and Christian ethics. {Chapter One} Firstly, in the examination of Abraham's act of faith in Fear and Trembling, I showed that even in this book there was a hint of a new ethics which follows from faith. To answer the question as to whether there is a clear description of this new ethics, I turned to Works of Love. In the examination of this book, I identified the ethics of Christian love, and asserted that the ethics of Christian love was different and discontinuous from merely human love. In the next section, I examined Christian ethics as the ethics of Christian discipleship. Through an examination of some parts of Philosophical Fragments and Training in Christianity I argued that Christian ethics, as understood by Kierkegaard, is different from merely ethical discipleship and semi-Pelagianism. Throughout this chapter's discussion I argued that Christian ethics was not only different from the ethics of the ethical person, but also antithetical to it. For ethics based on merely human love was criticized severely in Works of Love, and the merely ethical discipleship and semi-Pelagian discipleship were regarded as misunderstandings of Christian ethics. I turned, in the second chapter, to the consideration of the problem of becoming oneself. In this chapter, I firstly examined the second volume of Either/Or and argued that the ethical self was an autonomous self which tried to be itself by itself. In contrast, the Christian self is totally dependent on God in its becoming itself. I drew this conclusion from an examination of The Sickness unto Death. In this examination, I argued that even though there were some ambiguities in this book, despair as sin was clearly understood only by the Christian who believed in the forgiveness of sin by God and had faith. Only the existing individual who is in faith is regarded as overcoming the despair and having become a "self" (or "spirit"). I pointed out that in their understandings of the eternal, of the power of self, these two understandings of the self were different from one another. In the last section of this second chapter, I raised the question of the understanding of the self of the person in religiousness A. By an examination of the Socratic understanding of the phrase "one can be oneself in relation to God" and an analysis of Socratic inwardness, I argued that those in religiousness A had a different God, or different conception of God from the Christian God. I also argued that this difference between their respective conceptions of God was the fundamental reason for the difference between the Christian understanding of becoming a self and that of the person in religiousness A. In the third chapter, I examined the problem of epistemology. Firstly, I drew out, from Kierkegaard's various pseudonymous writings, the presuppositions and epistemological standpoint of the natural man. Then, I compared this with the Christian epistemological standpoint which was drawn from Kierkegaard's later writings. I argued that in his later writings there were very clear indications that the Christian has an epistemological standpoint which is substantially different from that of the natural man. I turned then to an examination of Kierkegaard's journal entries, and showed that even though he himself could not always think in the way which he asserted that the Christian should think, Kierkegaard did not compromise and say that it was proper and inevitable for us to mix the Christian standpoint and the natural man's standpoint. Rather, he strongly resisted the idea that such a mixture was Christian. Next I returned to one of Kierkegaard's early pseudonymous writings, philosophical Fragments, to show that Kierkegaard's ultimate intention in writing this book can be interpreted in a manner consistent with his later writings. I argued that even though, because of the ambiguity in this book, there are other ways of interpreting it, it is also possible that the Socratic standpoint and the Christian standpoint are too exclusive views of reality as a whole, and that even in this book Kierkegaard tried to show the difference and discontinuity of the Socratic (humanist) standpoint and the Christian standpoint. According to this interpretation of Kierkegaard's intention, he who has the Christian point of view should see and consider everything from the Christian standpoint; for him, there is no autonomous realm to be thought of from the Socratic (humanistic) standpoint. Based upon this examination, I concluded that for Kierkegaard Christian ethics follows on from Christian theology (his Christian theistic faith), and the understanding of becoming oneself also follows on from Christian's stance of faith (so that the Christian self is regarded as the “theological self”), and his epistemological standpoint is also Christian. In this sense, there is a wide gap between the Christian sphere and the ethical sphere, or to put this another way, their direction is different : one is theistic and one humanistic. For Kierkegaard, to be a Christian thus involves a change in one's ethics, in one's understanding of becoming oneself, and in one's epistemological standpoint. Then, I drew out some implications for Kierkegaard's theory of the existence-spheres as a whole and suggested some implications for Christian theology today.

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