This article aims to present the political theology of Joseph Ratzinger/Benedict XVI. The first paragraph focuses on Ratzinger’s interpretation of selected New Testament source texts and the basic assumptions of what he called the “service to politics rendered by the Christian faith.” The second paragraph deals with Ratzinger’s interpretation of the key relevant logion: “Render to Caesar the things that are Caesar’s and to God the things that are God’s” (Mark 12:17). It cut the knot of the legal, moral and cultic order, on which states based their status, regarding the binding character of its laws as an expression of the divine will. The Enlightenment, according to Ratzinger, was faced with the necessity of cutting the equation “in two,” this time in the Christian world, by exposing the Gospel-rooted model of separation of Church and State. The fundamental task of Christians then is to maintain the balance of the dual system as the basis of freedom. The third paragraph traces the development of Ratzinger’s reflection on the greatness and weaknesses of the contemporary vision of democracy. The clou of this reflection was the reference to the “Böckenförde paradox,” particularly topical in the era of the “dictatorship of relativism” that destroys democracy. The author refutes the criticism of the “Böckenförde paradox” made by Chantal Delsol in her book predicting the end of the Christendom, and concludes with a presentation of the Doctrinal Note on Some Questions Regarding the Participation of Catholics in Political Life (2002), which is, in his view, the culmination of Ratzinger’s thought on the foundations of politics in the light of fundamental theology and Catholic social teaching.