The Kingdom of Heaven—Holy Church—is seen bringing forth out of her treasure “things new  and old.” Although she can never add new dogmas to the deposit of Faith entrusted to her, as the ages go by she is seen understanding more perfectly and explaining more fully those treasures in her keeping. She is a living body, not a statue, and she can develop, though she can never change her nature. Hence, guided by the Holy Spirit of Him who has promised to be with her not merely for a few centuries but unto the end of  the world, she defines or emphasizes certain points of  doctrine as she sees fit, considering the needs of the times. We have an example in the institution of the feast of the Kingship of our Lord Jesus Christ by the  Sovereign Pontiff, Pope Pius XI, in the jubilee year 1925,  and explained to the faithful in the Encyclical Quas Primas.

Today we sadly behold “a world undone,”…At the best, governments mostly ignore God; and at the worst,  openly fight against Him. Even the statesmen’s well-meant efforts to find a remedy for present ills and, above all, to secure world peace, prove futile because,  whereas peace is from Christ…His name is never mentioned throughout their deliberations or  their documents. Christ is kept out of the State schools and seats of higher education; and the
rising generations seem to be taught anything and everything save to know, love and serve Him. Christians have ever hailed our divine Lord as King of Kings and Lord of Lords. It was as a  King that the representatives of the Eastern world came to adore him in the manger; it was as a  King, albeit not knowing what He did, that the official representative of the Western world lifted  Him up on the Cross. The patriarchs and prophets of the old dispensation foretold His royalty;  He spoke constantly of His kingdom: when asked plainly whether He were in truth a king by the representative of Caesar, He acknowledged that such indeed He was, though of a kingdom not  of this world…Christ is King over angels and men; King over men’s hearts and wills; His
Kingship demands of its subjects a spirit of detachment from riches and earthly things, and a spirit of gentleness. They must hunger and thirst after justice and, more than this, they must deny themselves and carry the cross.

The Liturgical Year, Vol. XIV, Book V, from Pgs. 473-475