Today (June 29) the Catholic Church celebrates one of its most ancient feasts - the Solemnity of Saints Peter and Paul. Although the exact origins of the feast are unclear, the Church was celebrating these two great apostles with a shared feast by the mid-third century. Both of the saints had served the Church in Rome and were martyred there during the persecutions of Emperor Nero.

It is the leadership and martyrdom of Sts. Peter and Paul that gave the Church of Rome its early prominence among the Churches of the world. Jesus had given to Peter the "keys of the kingdom of heaven" - a symbol of his authority to lead the rest of the Church - and the bishop of Rome (the "pope") was regarded as the successor of St. Peter. St. Paul, the "Apostle to the Gentiles," was the most zealous missionary of the Roman Empire, and his mission and martyrdom in Rome were seen as further proofs of the precedence of the Church of Rome.

The bishop of Rome was essential in maintaining the unity of the early Church in the truth of the Catholic faith and remains essential today. In the second century, for example, there were a number of renegade preachers who began to teach a heresy known as Gnosticism, claiming that they - not the bishops of the Church - knew the secret doctrines of Jesus. They began to write their own false gospels, drawing people away from the Church. St. Ireneaus, a second-century Greek bishop whose feast we celebrated yesterday, appealed to the authority of the apostles Sts. Peter and Paul to explain that those who wish to follow the true teaching of Jesus Christ must remain united with the bishops, especially the bishop of Rome:

Matthew also issued among the Hebrews a written Gospel in their own language, while Peter and Paul were evangelizing in Rome and laying the foundation of the Church.... But since it would be too long to enumerate in such a volume as this the succession of all the churches, we shall confound all those who, in whatever manner, whether through self-satisfaction or vainglory, or through blindness and wicked opinion, assemble other than where it is proper, by pointing out here the successions of the bishops of the greatest and most ancient church known to all, founded and organized at Rome by the two most glorious apostles, Peter and Paul, that church which has the tradition and the faith which comes down to us after having been announced to men by the apostles. With that church, because of its superior origin, all the churches must agree, that is, all the faithful in the whole world, and it is in her that the faithful everywhere have maintained the apostolic tradition. ( Against Heresies 3:3:1-2, c. 180-190)

St. Irenaeus then goes on to list the succession of bishops in the Church of Rome - Peter and Paul appointed Linus, who is mentioned in St. Paul's Second Letter to Timothy (2 Timothy 4:21). Linus was followed by Anacletus, then by Clement, who knew Peter and Paul personally and was instrumental in settling a dispute among the Corinthians. Irenaeus goes on to list each of the subsequent bishops of Rome, down to his own day.

The bold claim being made here by St. Irenaeus is that all Christians must remain in communion with the Church of Rome, because the bishop of Rome, the pope, traces his authority back to the great Apostles Peter and Paul. Will you listen to the new-fangled teachings of the Gnostics, he challenges, or to the teaching of the apostles that continues to be taught by the bishop of Rome?

This principle of unity and certainty remains true today - When a new YouTube or Twitter star comes along claiming to have the inside scoop about faith and morals, should we listen to them? What if that teacher claims to know better than the pope? Today, as in centuries past, the bishop of Rome "is the perpetual and visible source and foundation of the unity both of the bishops and of the whole company of the faithful" (CCC 882), which means that we must place our communion with the bishop of Rome over our communion with this or that online personality.

I'll admit, though, that the Catholic Church seems very divided and disorienting today, and even those who want to remain faithful to Catholic tradition can find themselves conflicted. On both the Left and the Right, Pope Francis has a reputation of being ready to compromise Catholic tradition in order to win the favor of the modern world. To some on the Left, this is often a cause of great delight: Finally, it is thought, we have a pope who is willing to set aside antiquated Christian doctrines and accept modern sensibilities. To some on the Right, this is instead the cause of great alarm: After nearly two thousand years of fidelity to tradition, it is thought, we have a pope who is caving in to secular progressivism.

Contrary to the narrative of some on both the left and the right, Pope Francis has not reversed Catholic teaching on any matters of faith and morals. What was true yesterday remains true today. Nor does Pope Francis, in fact, have the authority to innovate Catholic doctrine - The First Vatican Council explained:

[T]he Holy Spirit was promised to the successors of Peter not so that they might, by his revelation, make known some new doctrine, but that, by his assistance, they might religiously guard and faithfully expound the revelation or deposit of faith transmitted by the apostles ( Pastor Aeternus 6).

Regardless of who is pope, the Catholic faith assures us that the official teachings of the pope will preserve apostolic tradition and that communion with him is always essential. This does not mean that the decisions, interviews, off-the-cuff comments, or even homilies of a given pope are free from errors of judgment or of doctrine, but that whenever the pope officially teaches something as binding on the whole Church, then we can trust what he teaches and have a moral obligation to listen (see CCC 880-892 for more details). It also means that we should put the manifest, expressed teachings of the pope above the opinions of our favorite YouTube and Twitter personalities as we strive to be faithful to the Word of God, contained in Scripture and Tradition.

As we celebrate the great Solemnity of Sts. Peter and Paul, then, let us thank the Lord for the authority that he entrusted to them and that they in turn have entrusted to the bishop of Rome.