Encyclical letter of Pope Pius XI published Jan. 6, 1928 [Acta Apostolicae Sedis 20 (1928) 5–16]. It was a solemn treatise on the ecumenical movement as embodied in the life and work and faith and order Conferences. It was an explanation of Catholic nonparticipation in the Lausanne Conference of 1927. The pope forbade Catholic participation in a movement that he called "panchristian." The reasons were: the postulates of the union denied that the Church of Christ already visibly exists in the world and affirmed that it must be brought into existence; they implied that reunion can be achieved without unity of doctrine; they inferred that the Catholic Church is not the Church of Christ but one of many communities in His Church. These postulates involved relativism in doctrine, modernism in theology, and indifferentism in ecclesiology. Any meeting or association or movement based on such principles would contradict the entire faith of the Church, so that no Catholic could in logic take part in them. This encyclical was not well received by non-Catholics, but by its clear presentation of principles it served to pave the way for Catholic ecumenical activity in another generation. It was referred to in the instruction of the Holy Office of Dec. 20, 1949, on the ecumenical movement [Acta Apostolicae Sedis 42 (1950) 142–147].
Bibliography: s. boulgakov, "The Papal Encyclical and the Lausanne Conference," The Christian East 9 (Autumn 1928). a. d. lee ed., Vatican II: The Theological Dimension (Washington 1963). g. baum, That They May Be One: A Study of Papal Doctrine, Leo XIII-Pius XII (Westminster, Md. 1958). y. m. j. congar, Lexicon für Theologie und Kirche, ed. j. hofer and k. rahner (Freiburg 1957–65) 7:1128–37.
[t. f. cranny]