The interests of the church in general, that they shall not sink, or be run down; underneath the church is that rock of ages on which it is built, and against which the gates of hell shall never prevail, Mt. 16:18. (Henry, Matthew. on Dt 33:26)
First, Some by this rock understand Peter himself as an apostle, the chief, though not the prince, of the twelve, senior among them, but not superior over them. The church is built upon the foundation of the apostles, Eph. 2:20. The first stones of that building were laid in and by their ministry; hence their names are said to be written in the foundations of the new Jerusalem, Rev. 21:14. Now Peter being that apostle by whose hand the first stones of the church were laid, both in Jewish converts (Acts 2), and in the Gentile converts (Acts 10), he might in some sense be said to be the rock on which it was built. Cephas was one that seemed to be a pillar, Gal. 2:9. But it sounds very harsh, to call a man that only lays the first stone of a building, which is a transient act, the foundation on which it is built, which is an abiding thing. Yet if it were so, this would not serve to support the pretensions of the Bishop of Rome; for Peter had no such headship as he claims, much less could he derive it to his successors, least of all to the Bishops of Rome, who, whether they are so in place or no, is a question, but that they are not so in the truth of Christianity, is past all question.
Secondly, Others, by this rock, understand Christ; "Thou art Peter, thou hast the name of a stone, but upon this rock, pointing to himself, I will build my church.'' Perhaps he laid his hand on his breast, as when he said, Destroy this temple (Jn. 2:19), when he spoke of the temple of his body. Then he took occasion from the temple, where he was, so to speak of himself, and gave occasion to some to misunderstand him of that; so here he took occasion from Peter, to speak of himself as the Rock, and gave occasion to some to misunderstand him of Peter. But this must be explained by those many scriptures which speak of Christ as the only Foundation of the church; see 1 Co. 3:11; 1 Pt. 2:6. Christ is both its Founder and its Foundation; he draws souls, and draws them to himself; to him they are united, and on him they rest and have a constant dependence.
Thirdly, Others by this rock understand this confession which Peter made of Christ, and this comes all to one with understanding it of Christ himself. It was a good confession which Peter witnessed, Thou art the Christ, the Son of the living God; the rest concurred with him in it. "Now,'' saith Christ, "this is that great truth upon which I will build my church.'' 1. Take away this truth itself, and the universal church falls to the ground. If Christ be not the Son of God, Christianity is a cheat, and the church is a mere chimera; our preaching is vain, your faith is vain, and you are yet in your sins, 1 Co. 15:14-17. If Jesus be not the Christ, those that own him are not of the church, but deceivers and deceived. 2. Take away the faith and confession of this truth from any particular church, and it ceases to be a part of Christ's church, and relapses to the state and character of infidelity. This is articulus stantis et cadentis ecclesia-that article, with the admission or the denial of which the church either rises or falls; "the main hinge on which the door of salvation turns;'' those who let go this, do not hold the foundation; and though they may call themselves Christians, they give themselves the lie; for the church is a sacred society, incorporated upon the certainty and assurance of this great truth; and great it is, and has prevailed. (on Mt. 16:18)Be careful here.
[Edited on 5-31-2004 by fredtgreco]