祁克果以託名論著的《致死的疾病》與《害怕的概念》二書，主旨都在於探討基督教「罪」的概念，都以人的生存中常可經歷到的心理現象為觀點，從而重新詮釋基督教的罪論。這也是祁克果神學著作的獨特性，在反省基督教教義、與神學傳統對話的同時，更期望他的論述帶給人靈性上清晰的亮光，得以看見基督信仰與人的存在具體對遇之處。本文將首先論述《致死的疾病》由人的生存普遍帶有的現象所詮釋的基督教罪觀，並與《害怕的概念》進行文本互涉。再來將討論布特曼藉由祁克果的觀點繼續發展的，以意志／抉擇的議題做為人的存在的根本問題。最後，於結論中則有一些篇幅與當今認知神經科學的研究對話，說明祁克果論述罪觀的進路對於現今神學研究的通切性。

"The Sickness unto Death" and "The Concept of Anxiety" were written by Kierkegaard's pseudonymous authorship. Both of them discuss about the concept of sin in Christianity and from the perspective of psychological phenomena in human existence reinterpret the harmatology. That is Kierkegaards writing character, he reflected Christianity and discussed with theological tradition but at the same time be rather expected, that his theses could bring clear light to the readers, in order that they could see the exact encounter between Christianity and their existence. In this text I should first illustrate the concept of sin in "The Sickness unto Death", which is developed through analyzing the phenomena of human existence. Then, I should discuss Bultmann's issues about the will/decision and the human existence, which are unfolded on the base of Kierkegaard's perspective. At the conclusion I should also talk with some researches of cognitive science and explain that the approach of Kierkegaard's harmatology still has its appropriateness for the current theology.