Title: That they be one
Subjects: 20th century, Catholic Church, Christian sociology, Doctrines, History, History of doctrines, Papal documents, Sociology, Christian (Catholic), Katholieke sociale leer, Doctrinal Theology, Christliche Sozialethik, Enzyklika, Katholische Soziallehre, Geschichte (1700-1980), Geschichte (1740-1989), Encyclieken, Papst, Catholic church, doctrines
Time periods: 18th century, 19th century, 20th century