The overarching aims of this text are to demonstrate that understanding the often overlooked Purity of Heart is essential to understanding Søren Kierkegaard's Christian ethics and to illuminate what ethical insights Kierkegaard provides. For those scholars who have turned their attention to Purity of Heart, various issues and problems persist. First, there remains confusion over the text's "religiousness"—whether it is rightly designated as a "Religiousness A" or "Religiousness B" text. A second major issue surrounding Purity of Heart is the text's relation to Kantianism. Many scholars see the text as incorporating and even representing many of Kant's views. I correct that prevailing view, and in doing so, I also rectify a perpetual misunderstanding of Kierkegaard's view of eternal happiness and the Good. Third is the issue of integrity. I show that Purity of Heart provides a unique account of Christian integrity. I also make the claim that, even though Kierkegaard does not recognize it, his account suggests that integrity is sometimes worth losing. Fourth is the matter of suffering. Kierkegaard spends a great deal of time discussing what he calls "essential" suffering. Purity of Heart is the only text that considers this kind of suffering. I explain how Purity of Heart's concept of "essential suffering" is a unique form of Christian suffering. Fifth is the issue of interpersonal relations. Purity of Heart is fundamentally a text about intra-personal relations. However, towards the end of the text, Kierkegaard provides some thoughts on how this intra-personal purity can be extended to interpersonal relations. I show that intra-personal purity affects not only those interpersonal matters presented in Purity of Heart but also one raised in the Concluding Unscientific Postscript, the contemporary problem of the "Sunday-Monday gap."