Solemni Hac Liturgia (Credo of the People of God)
Fr. Maderak spoke this weekend about an Apostolic letter written by Pope Paul VI in 1968 during a time of confusion when many were mis-interpreting the documents of Vatican II and replacing them with the "Spirit of Vatican II", with little regard for the actual content of the documents. SOLEMNI HAC LITURGIA (Credo of the People of God) was written to clarify and solidify the teachings and beliefs of the Catholic Church. The mandate of this letter is best summarized in the 4th paragraph:
In making this profession, we are aware of the disquiet which agitates certain modern quarters with regard to the faith. They do not escape the influence of a world being profoundly changed, in which so many certainties are being disputed or discussed. We see even Catholics allowing themselves to be seized by a kind of passion for change and novelty. The Church, most assuredly, has always the duty to carry on the effort to study more deeply and to present, in a manner ever better adapted to successive generations, the unfathomable mysteries of God, rich for all in fruits of salvation. But at the same time the greatest care must be taken, while fulfilling the indispensable duty of research, to do no injury to the teachings of Christian doctrine. For that would be to give rise, as is unfortunately seen in these days, to disturbance and perplexity in many faithful souls (Solemni Hac LIturgia 4).\
You can read the whole apostolic letter
HERE.