A b s t r a c t. The article presents the achievements of Cardinal Stanisław Nagy in the field of ecclesiology, including the ecumenical context. The main problem is the primacy of the Bishop of Rome as the supreme office in the Catholic Church. The article presents the apologetic argumentation concerning the truthfulness of the Church, called via primatus. It describes the ministry of primacy as the function of St. Peter the Apostle and his successors, conferred upon him by Jesus Christ with

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... e purpose to ensure the unity and permanence of the Church. The article also addresses the problem of ecumenical quest, for which the person of the pope is the most difficult obstacle in the process of unifying Christianity. The last part of the article presents the praxeological aspect of the ministry of primacy in the pontificate of John Paul II.