Pope Pius XI issued the papal encyclical 'Quas primas' to formally institute the Feast of Christ the King, which would be celebrated on the last Sunday of October. The encyclical emerged in response to growing secularism and the challenges posed by modernity, which the Pope believed undermined the rightful place of Christ in society and governance. Pius XI intended to remind the faithful of the supremacy of Christ over all aspects of life, particularly in a rapidly changing world dominated by political ideologies and materialism.

In 'Quas primas', the Pope called for the faithful to acknowledge Christ's kingship in their lives, emphasizing the importance of recognizing His authority not only in personal faith but also in societal matters. By establishing a feast day dedicated to Christ the King, Pius XI hoped to reclaim the space that secular ideologies had occupied within society. The encyclical outlines the significance of this feast in promoting the reign of Christ, encouraging believers to reflect on their relationship with the divine amidst contemporary societal challenges.

The Feast of Christ the King quickly gained traction, becoming widely celebrated in the Catholic Church. Over the years, it has served as a liturgical reminder of the Church's mission to proclaim Christ as King, even amidst a backdrop of diminishing religious influence across the globe. The feast also prompted theological discussions surrounding the relationship between faith and politics, prompting further reflection on the role of the Church in modern society and the responsibility of Christians to reflect Christ's teachings in the public sphere.