Papal infallibility. What is it? Does it mean the pope cannot sin? Does it mean he is perfect? Since when is the pope infallible?
Papal infallibility is used by the pope during formal teaching, or the Formal magisterium, mentioned previously at the start of this article series on the pope. This form of the teaching Magisterium is that which is used by popes to formally define articles of the faith infallibly. When the pope teaches this way, it is referred to as ex cathedra.
The notion of Papal infallibility dates back to the teachings of Christ to the Apostles. Christ told His Apostles that the Holy Spirit would guide them in all truth (John 16:13), as they had been given the job of teaching everyone the things Christ had commanded (Matthew 28:19-20). Speaking through His Apostle Paul, Christ taught the deacon Timothy that the Church is the pillar and ground of truth (1 Timothy 3:15). Christ’s Church is the ground of truth. It cannot err in its doctrinal teachings. If it would, it would not be the pillar of truth.
How is this applied to the teachings of the Church today? Yes, the Church is the pillar of truth, but who exactly defines the teachings? One cannot just say “the Church”. The Church is much more than just a vague expression.
The pope, the successor of Peter, enjoys the protection of infallibility when formally pronouncing Catholic doctrine. When doing this, speaking ex cathedra, the pope does not invent doctrinal beliefs; he defines them. Any beliefs formally defined by the pope were not news to Christians — they were long held beliefs. The protection from error does not equate to invention of doctrine.
Neither does infallibility mean that a pope cannot sin. Popes sin. Many have been horrible sinners. But sin doesn’t effect infallibly protected teaching. Peter was a sinner, and yet he made an infallible teaching at the Council of Jerusalem (Acts 15:6-30).
Infallibility has nothing to do with the private lifestyle of the pope. Infallibility prevents a pope from solemnly and formally teaching error as a truth. It has nothing to do with the state of his soul, or how many sins he commits. It merely prevents him from solemnly and formally teaching error.
— Patrick Devens