Mystici corporis Christi (June 29, 1943) is a
papal encyclical issued by
Pope Pius XII during
World War II, on the
Church as the Mystical Body of Christ. It is one of the more important
encyclicals of Pope Pius XII, because of its topic, the Church, and because its Church concept was fully included in
Lumen gentium but also strongly debated during and after
Vatican II. The Church is called body, because it is a living entity; it is called the body of Christ, because Christ is its Head and Founder; it is called mystical body, because it is neither a purely physical nor a purely spiritual unity, but supernatural. It followed the commencement of
Nazi Germany's programs of "
euthanasia" of the handicapped, and
race-based murders of Jews and other minorities, and is therefore significant for its reiteration of Church teachings against racism and the killings of people with disabilities.