How do we know the pope can make an infallible statement of doctrine?
The short answer
Christ gave infallibility to Peter and his successors, as Scripture shows (Luke 22:31-32; Matthew 16:18-19). The early Christians understood the pope's primacy, which involved infallibility, but it was formally defined only at the First Vatican Council, once it was disputed.
Christ bestowed infallibility on Peter and his successors, and Scripture shows it:
- "Simon, Simon, behold Satan has demanded to sift all of you like wheat, but I have prayed that your own faith may not fail; and once you have turned back, you must strengthen your brothers" (Luke 22:31-32).
- "And so I say to you, you are Peter, and upon this rock I will build my church, and the gates of the netherworld shall not prevail against it. I will give you the keys to the kingdom of heaven. Whatever you bind on earth shall be bound in heaven; and whatever you loose on earth shall be loosed in heaven" (Matthew 16:18-19).
Early Christians understood Christ's teaching on the pope's primacy, which involved infallibility. But papal infallibility was not infallibly defined until the First Vatican Council, because there was no need to define it formally until it was disputed; infallible pronouncements are usually made only when a doctrine has been challenged.