On the Obligation of the State to Recognize Christ the King

"Nations will be reminded by the annual celebration of this feast that not only private individuals but also rulers and princes are bound to give public honor and obedience to Christ. It will call to their minds the thought of the Last Judgment, wherein Christ, who has been cast out of public life, despised, neglected, and ignored, will most severely avenge these insults; for His Kingly dignity demands that the State should take account of the Commandments of God and of Christian principles, both in making laws and in administering justice, and also in providing for the young a sound moral education."

Pope Pius XI, Quas Primas (December 11, 1925), 32.