The papacy is one of the most distinctive features of Catholicism. Catholics believe that Jesus established Peter as the head of the apostles and the leader of his Church, and that this authority has been passed down in an unbroken line of succession to the present-day Pope.

The biblical foundation for the papacy is found primarily in Matthew 16:18-19, where Jesus says to Peter: "You are Peter, and upon this rock I will build my church... I will give you the keys of the kingdom of heaven." The "keys of the kingdom" imagery refers to the authority given to a chief steward in ancient Israel — a role of governance and authority under the king.

Peter exercised this leadership role in the early Church. He was the first to preach at Pentecost (Acts 2), presided at the Council of Jerusalem (Acts 15), and was recognized as having a unique authority among the apostles. He eventually traveled to Rome, where he served as bishop until his martyrdom under Emperor Nero.

The Pope's authority includes teaching on faith and morals, governing the universal Church, and serving as a visible sign of unity among all Catholics worldwide. Under specific conditions, the Pope can speak "ex cathedra" (from the chair of Peter) on matters of faith and morals with infallibility — meaning the Holy Spirit preserves him from error in those solemn declarations.

Infallibility does not mean the Pope is sinless or that every statement he makes is infallible. It is a narrowly defined charism that applies only in specific, formal circumstances.