Summi Pontificatus (On the Unity of Human Society)

Summi Pontificatus (On the Unity of Human Society) explores the need for the Christian message in a time of turmoil. It affirms the "supernatural brotherhood of peoples" despite the scourge of war and laments the unbelief that has contributed to widespread moral collapse. Pius XII identifies two particularly dangerous errors. First, some deny the fundamental unity of humanity. Pius asserts that this unity is enriched, rather than threatened, by diversity in culture and economic development, and he cautions that love of nation should never overpower the "all-embracing nature of Christian Charity." The second error is that some desire to make the state the ultimate moral authority, rejecting the divine foundation of justice and threatening the responsible independence of families and economic actors. Pius calls on nations to peacefully observe international law, offering a specific lament for the invasion of Poland. The encyclical closes by urging constant prayer for peace and unity.