Tu es Petrus et super hanc petram aedificabo ecclesiam meam

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. - Matthew 16:18

Today is the feast of the Chair of St. Peter.

Few verses of scripture elicit heated debate in such a manner as Matthew 16:18. For Catholics, this verse defines the role of St. Peter as chief of the apostles. Jesus asks the disciples who they say he is, and Simon speaks up and says that Jesus is the "Messiah, the Son of the living God." For his faith, Jesus gives Simon the new name "Peter" which is translated from Greek as "rock" or "stone".

Catholics say that St. Peter's faith in Christ and his confession is the "rock" on which the Church is built. Orthodox and Protestants will agree that the "rock" is the faith which is the foundation of the Church. Where we disagree is that Catholics say that St. Peter himself is the personification of that faith in Christ, and because St. Peter was given the keys to the kingdom of Heaven, keys which are symbolic of the dynastic authority which is to be handed on to his successors, the Bishops of Rome, they will therefore hold the keys as well and will become the personification of that faith in Christ, living symbols of the faith of the Church.

Jesus himself defines the source of the Church's faith when he says, “Blessed are you, Simon son of Jonah. For flesh and blood has not revealed this to you, but my heavenly Father." (Matthew 16:17) The faith of which St. Peter is the personification comes from above, and since it is derived from God, it is without error. Therefore, when the Pope, the successor to St. Peter as Bishop of the Church in Rome, speaks on matters concerning this inerrant faith, his words are protected from error as well. This does not mean that the Pope is incapable of making a mistake (because even the Pope goes to confession). It means that God is incapable of making a mistake.

When we profess our faith that Jesus is the Messiah, the Son of the living God, Christ calls each of us blessed as well and reveals to us that the Father is the source of that profession of faith. The faith which all Catholics profess and which unites us is most visible in the man who sits in the Chair of St. Peter, the man who confirms his brothers and sisters in that faith, the man chosen by Christ to tend his flock, the man who holds the keys to Christ's kingdom. While our faith is the "rock", we are not. That title is reserved for him who holds the keys. This is what we celebrate today.

Holy Father Peter, pray for us.