Q. 1. What does "infallibility of the Church" mean?
A. 1. Infallibility of the Catholic Church means that the Church, through the guidance of the Holy Ghost (Spirit), it cannot err when it teaches or believes a doctrine of faith and morals.
Jesus promised: "All power in heaven and on earth has been given to me. Go, therefore, and teach all nations... teaching them to observe all that I have commanded you; and behold, I am with you all days, even unto the consummation of the world." [Matt. 28:20] If Jesus is with the Catholic Church "all days," the Church cannot err in teaching; it cannot lead men away from God.
It should be noted that an infallible Bible is of no use without an infallible interpreter. History has proved this, in the multiplication of the innumerable denominations that deny the infallibility of the Church. By infallibility, the faithful know exactly what to believe and what to do in order that they may be pleasing to God and save their souls. They have surety; they need suffer no doctrinal doubt.