Benedict XVI taught against the new phenomenon of ultramontane Progressivism: the zeitgeist (the spirit of the times) can never serve as the basis of either faith or doctrine:

“This power of teaching frightens many people in and outside the Church. They wonder whether freedom of conscience is threatened or whether it is a presumption opposed to freedom of thought. It is not like this. The power that Christ conferred upon Peter and his Successors is, in an absolute sense, a mandate to serve.

The power of teaching in the Church involves a commitment to the service of obedience to the faith. The Pope is not an absolute monarch whose thoughts and desires are law. On the contrary: the Pope’s ministry is a guarantee of obedience to Christ and to his Word. He must not proclaim his own ideas, but rather constantly bind himself and the Church to obedience to God’s Word, in the face of every attempt to adapt it or water it down, and every form of opportunism.

Pope John Paul II did this when, in front of all attempts, apparently benevolent to the human person, and in the face of erroneous interpretations of freedom, he unequivocally stressed the inviolability of the human being and of human life from the moment of conception until natural death. The freedom to kill is not true freedom, but a tyranny that reduces the human being to slavery.

The Pope knows that in his important decisions, he is bound to the great community of faith of all times, to the binding interpretations that have developed throughout the Church’s pilgrimage.

Thus, his power is not being above, but at the service of, the Word of God. It is incumbent upon him to ensure that this Word continues to be present in its greatness and to resound in its purity, so that it is not torn to pieces by continuous changes in usage.”

Benedict XVI
Homily
May 7, 2005