Luke 10:16: “He who hears you hears me, and he who rejects you rejects me, and he who rejects me rejects him who sent me.”
Matthew 16:18: “And I tell you, you are Peter, and on this rock I will build my church, and the powers of death (gates of hell) shall not prevail against it.”
Malachi 2:7: For the lips of a priest should guard knowledge, and men should seek instruction (law) from his mouth, for he is the messenger of the Lord of hosts.
The Holy Spirit has functioned as the very soul of the Catholic Church, insuring the efficacy of the sacraments and the truthfulness of official interpretations of the Word of God and his will for us. Certain Protestants claim an immediate mastery of all Scripture as long as they approach it prayerfully and with care. However, the Holy Spirit is not like a light switch that we can turn immediately off and on. While not utterly invalidating the personal meanings we might find in bible reading, we leave the authoritative renderings to the Magisterium (Pope and bishops in union with him). It is interesting that the fundamentalist Protestant claim makes more a claim upon the Holy Spirit and infallibility than does the Pope, himself. He only offers a declaration after extended investigation and consultation, and even then, after much prayer. Unless it is a matter essential to the faith, he usually does not invoke this authority. Infallible papal declarations are quite rare. The Pope does not make something true; rather, he draws our attention to what we have always believed.