Matthew 16:18 is a problem for Lutherans and Roman Catholics. Rome points to Peter and the Petrine office of the papacy. Jesus is pointing to a man, rather a succession of men, whose primacy is, in their view, undisputed. Lutherans insist that Peter may have been the voice but it is the confession that is the rock. This faith is the rock upon which the Church is built -- not a man but the confession that Jesus Christ is Lord. Lutherans insist that this is affirmed in Jesus' own admonition that Peter did not confess this on his own but as the Father revealed it to Him. Now surely this is a rather simplistic way of putting it and there are nuances on both sides that I have overlooked to put this into a brief paragraph. But allow me this for the moment.
I must say that I have had trouble with both views. Every time I suggest that the LCMS aversion to Bishops should be overcome, there are commenters who insist that an episcopal system is no more a guarantee of orthodox faith and practice than the synodical structure of this branch of Lutheranism. Some delight in pointing out the fallible men who have used their good office to voice apostasy (from the Pikes to the Spongs to the Robinsons to a host of others, not only Anglican).
On the other hand, the idea that the faith is floating out there disembodied from the church (the baptized who confess the faith of the creed and who gather in the name of Jesus around His Word and Table) is likewise unsettling. We speak not of a faith in theory but of a faith expressed in words, confessed in creeds and confessions, and said in the mouth of real people. The Church is not virtual or theoretical but where the Word is rightly preached with the Law and Gospel rightly distinguished and the Sacraments are rightly administered as Christ instituted them. The Church in its fullness may be invisible but this is of little comfort or solace to me the sinner. I look for the visible Church known by her marks and manifest in the evangelical and catholic confession and practice of the means of grace.
Athanasius said: It will not be out of place to consider
the ancient tradition, teaching and faith of the Catholic Church, which
was revealed by the Lord, proclaimed by the apostles and guarded by the
fathers. For upon this faith the Church is built, and if anyone were to
lapse from it, he would no longer be a Christian either in fact or in
The problem lies with taking either to the extreme -- that Christ built His Church upon a man and that apostolic succession is the mark and guarantee of its faithfulness or authenticity OR that the confession of faith is so distinguished from those confessing that Jesus is referring here to creedal content and not creed confessed in the mouths of people. The faith is the faith believed, confessed, and taught. The succession is not of men in a chain but of the Church -- Pastors and people, confessing Jesus Christ faithfully, and gathered around the Word and Table of the Lord. The Church exists not in theory but in concrete reality. The faith exists not in theory but in the concrete reality of voices speakinng together with the saints of old, keeping the sacred deposit and passing it on.
When churches lapse from this faith and confess a different teaching, they are no longer reliable and their whole confession is tainted. It is not that churches are wrong on small points but right on the big ones. There is no degree of orthodoxy with which any church may be satisfied and there is no justification for departing from the faith once delivered to the saints. The problem today is that we are no longer sure there is or ever was a faith once delivered to the saints and so we have a very broad view of orthodoxy -- one that fits our modern skepticism over the Scriptures and what it is that they say. We no longer have confidence that doctrinal unity is either possible or necessary. Athanasius would not have much to do with such churches.
When church leaders (Bishops and Pastors) depart from this faith and confess a different teaching, they have already surrendered their office. It is not that the standard of orthodoxy is so narrow that only a few comply or that the definition of orthodoxy so vague as to allow everyone's private opinions as legitimate. Orthodox Christian doctrine and practice are well known; it is our confidence in them that lacks. The problem today is that churches hold no one accountable. It is not that anyone has to satisfy me. That is hardly the point at all. But we have creeds and, as Lutherans, Confessions that do bind us -- and not merely our consciences but our voices and our actions. Athanasius would have little to do with those clergy who believe the pulpit and classroom is there to voice their own take on things or to express their doubts about what has been passed down from the saints.
Faithful confession and faithful people go hand in hand. The truth is not so difficult to find that we excuse error. Error is not so difficult to identify that we can have no certain truth. Creeds and confessions came from the voices and pens of the faithful. We receive them as our teachers and guides, we voice them in our own day, and we pass them on to those who come after us. The evangelical and catholic faith is confessed by confessors and on this Jesus builds His Church and the gates of hell shall not prevail. The many voices speaking as one, in accord with the saints, with faithfulness and clarity before the world today, and in faithfulness to those who come after us. All of this is the work of the Spirit whom the Father has sent to make the truth known.
The content of this creedal confession is for another post but suffice it to say it is the mystery of the Trinity, the mystery of the incarnation, and the mystery of the atonement. Look no further for the starting point of the content than to the three ecumenical creeds and, especially, the creed named for Athanasius. The catholic faith is this. Apart from which no one can or will be saved.
It would seem to me that Jesus is pointing and pushing us to two profound truths. Faith is not the discovery of men but the revelation of the Father working through the Spirit and faith is not theoretical but incarnate -- believed and confessed in people. It would seem that much error has crept in the Church by confusing this -- and more than merely about this one passage means!