In 1925 Pope Pius XI asked Édouard Hugon, professor of philosophy and theology at the Pontifical University of Saint Thomas Aquinas, Angelicum to work on Quas Primas.
Purpose and Content
“While nations insult the beloved name of our Redeemer by suppressing all mention of it in their conferences and parliaments, we must all the more loudly proclaim his kingly dignity and power, all the more universally affirm his rights.”
In response to this worldwide phenomenon of nations claiming more authority over the Church, the Pope also asserted the Church's right to be free from secular authority.
“When we pay honor to the princely dignity of Christ, men will doubtless be reminded that the Church, founded by Christ as a perfect society, has a natural and inalienable right to perfect freedom and immunity from the power of the state; and that in fulfilling the task committed to her by God of teaching, ruling, and guiding to eternal bliss those who belong to the kingdom of Christ, she cannot be subject to any external power.” 
The encyclical summarizes both the Old Testament and the New Testament teaching on the kingship of Christ. Invoking an earlier encyclical Annum Sacrum of Pope Leo XIII, Pius XI suggests that the kingdom of Christ embraces the whole mankind.
Significance for the Laity
While the encyclical was addressed to Catholic bishops, Pope Pius XI wanted the feast of Christ the King to impact the laity.
"The faithful, moreover, by meditating upon these truths, will gain much strength and courage, enabling them to form their lives after the true Christian ideal. If to Christ our Lord is given all power in heaven and on earth; if all men, purchased by his precious blood, are by a new right subjected to his dominion; if this power embraces all men, it must be clear that not one of our faculties is exempt from his empire. He must reign in our minds, which should assent with perfect submission and firm belief to revealed truths and to the doctrines of Christ. He must reign in our wills, which should obey the laws and precepts of God. He must reign in our hearts, which should spurn natural desires and love God above all things, and cleave to him alone. He must reign in our bodies and in our members, which should serve as instruments for the interior sanctification of our souls, or to use the words of the Apostle Paul, as instruments of justice unto God." 
Feast of Christ the King
Some have mistakenly believed that the placement of the feast on the last Sunday of Ordinary Time Pentecost, in the later Mass of Paul VI Novus Ordo calendar symbolized a new orientation of the Second Vatican Council in that Christ will reign, not now among nations, but at the end of time. However, such an interpretation is ultimately flawed as it relies on misunderstanding of the Council as replacing previous teaching, whereas it is actually in continuity with all that was taught by the Church prior to 1962. In fact, Christ's kingship is to occur both here and now, and at the end of time.
- Hugon O.P., Édourad. "Fuori della Chiesa non cè salvezza", Accessed Feb. 6, 2013
- Pope Pius XI, Quas Primas, §28, Libreria Editrice Vaticana
- Pope Pius XI, Quas Primas, §25, Libreria Editrice Vaticana
- Pope Pius XI, Quas Primas, §31, Libreria Editrice Vaticana
- Pope Pius XI, Quas Primas, §33, Libreria Editrice Vaticana
- "Solemnity of Christ the King". Catholic Culture. Retrieved 27 November 2013.