The article is devoted to the role of Christianity in building a political identity of the EU. The author analyzes the theological ideas of Joseph Ratzinger/ Benedict XVI. In his theological works, Ratzinger argues that the difficulties in achieving an EU general political dimension are closely linked to the denial of the socio-cultural heritage of Christianity. The definition of democratic and liberal citizenship, as well as the assertion of the principle of pluralism in European political culture, are not associated with Christian ethics. The author concludes that the rejection of Christian roots is the cause of the increasing political apathy in the EU. However, the motto “United in diversity”, on the basis of which the current EU leaders are trying to build a European political identity, is practically and theoretically compatible with the recognition of the role of Christianity, which historically has been and remains an integral part of this identity. © 2020 Institute of Europe Russian Academy of Sciences. All rights reserved.