The article is a topic outline of the theology of the Church’s unity. It shows the spectrum of contemporary reflection on this attribute of the Church mentioned in the Nicene-Con-stantinople Symbol (credo in unam Ecclesiam). The reflection includes biblical categories, especially the idea of koinōnia/communio, emphasizing the Trinitarian basis for unity of the Church, and its concrete means – bonds of unity. Among these means of unity, particular attention is paid to the bond of faith, the sacraments and ecclesiastical governance, nota-bly the universal ministry of Christian unity. Individual Churches (denominations) have different visions of unity, but also these concepts are the subject of ecumenical dialogue. The most recent ecumenical vision on the Church, including its unity, is the document of the World Council of Churches Commission on Faith and Order, Towards a Common Vision of the Church (published in 2013). Christian Churches involved in the contemporary ecumenical dialogue are aware that the unity of the Church is a reality given and set, yet incomplete and imperfect, so to speak “on the way”. In this sense they can express their spero in unam Ecclesiam.

The article compares two models of the Church government, which since Vatican II are often in a certain antagonism in the Catholic Church. The model of „Communio” builds the Universal Church from the local church (i.e. the diocesis); the model of „Iurisdictio” (or „Hierarchy”) starts from the primacy of jurisdiction of the bishop of Rom (and separates „ordo“ and „iurisdictio”) The author proposes (with Walter Kasper) a synthesis of „iuris-dictio” and „ordo” as a theological theme for the third Christian millennium. A special place is given to the discussion of the ecclesiology of Joseph Ratzinger, who demonstrates a development from the significance of the collegiality of the episcopate to the „martyria” of the single bishop in the relation of primacy and collegiality

Joseph Ratzinger discusses papal primacy in the Church, which is a communio based on the relationship between primacy and collegiality. Therefore, he supports jurisdictional primacy executed not in a monarchical way, but collegially, with the Pope as the head of the college of bishops. Joseph Ratzinger discusses the Petrine primacy in the New Testament, which he considers a starting point for a discussion about the succession of Peter’s office, choosing (via media) between papalism and conciliarism. He, therefore, focuses on the personal aspect of primacy connected with a given person. Moreover, the article discusses the relationship between the papacy and doctrinal infallibility. It also poses the question whether after his renunciation Benedict XVI still retains the charisma of doctrinal infallibility (or authentic orthodoxy) and how this refers to the current Pope Francis.