The Feast of Christ the King was established by Pope Pius XI to celebrate the Jubilee Year and 16th centenary of the Council of Nicea. In his encyclical letter issued on this noble occasion on Decemebr 11, 1925, the Pope brings to our attention traditional and biblical sources confirming the sovereignty of Our Lord Jesus Christ. He also explains the need for special liturgical celebration of the universal Church each year on the last Sunday of the liturgical year before the first Sunday of Advent.
"You, my God, are an eternal King, and Yours is no borrowed kingdom...When the Credo says: 'of Your Kingdom there shall be no end' this phrase nearly always makes me feel particularly happy. Yes, I praise You, Lord, and bless You, for Your Kingdom will endure forever" (St Teresa of Jesus, Way of Perfection, ch 22)