This chapter focuses on the diverging views Hans Kelsen and Reinhold Niebuhr held with respect to the relationship of religion and democracy. Kelsen leveled his criticism of Niebuhr in his essay on the "Foundations of Democracy" published in the October 1955 issue of the journal Ethics. Unfortunately, it seems Niebuhr was unaware of Kelsen's essay. However, Niebuhr's extensive writings on democracy provide a solid basis for a serious response to Kelsen. Beyond the specifics of Kelsen's article, this chapter draws on Kelsen's broader writings to expand the engagement between him and Niebuhr by analyzing their respective views on (1) the liberal tradition; (2) Christianity and democracy; (3) religion, totalitarianism and democracy; (4) pre-conditions and portability of democracy; and (5) justice, liberty and equality.