...it is treachery to the cause of true unity to refuse to point out obvious departures from the faith—regardless of the honored position of the one departing: “If we or an angel from heaven . . .” (Gal. 1:8). If there really were an unbroken magisterium, a united confession going back to the apostles, a unanimous consent of the fathers, no one would be more excited about it than I. But when such authority is claimed, and cannot be established from the Scriptures, and contradicts itself in a thousand ways even when evaluated in accordance with its own principles, a faithful minister can only label it as a deception. But pastors are to labor to this end of unity by speaking the truth in love, in order that the already unified body might become unified. We are growing up into our head, the Lord Jesus Christ. From Him, the whole body is being joined together—and the picture here of being joined and compacted as every joint supplies is an image of being knit together in the womb (Eph. 4:15–16). There is an essential unity in an embryo, but there is also a much higher unity toward which the embryo is growing. Many complaints about the “disunity” of the Church are actually complaints about how God knits in the darkness of the womb. We look over His shoulder and have the temerity to criticize what He is doing there. But we must go by what the Word says, and not by what we see. So as we grow up toward this unity, to extend the metaphor, we necessarily fight false teachers who want to introduce their birth defects into the process. As we love one another in all humility and stand for the truth in love, we advance the cause of unity in truth. God directs how this process will finally culminate. Our task is not to oversee the whole process, but rather to be faithful and obedient in our small portion of it. We therefore affirm a doctrine of apostolic succession, but this is not a succession of ordinations. That is not the basis of unity. Rather, it is a succession of baptisms, and all that those baptisms represent. One Lord, one faith, one baptism...But we receive our inheritance from our Christian past, and we perpetuate it as we evangelize nonbelievers and bring up our children in the faith. We do so by means of Word and sacrament, preaching and baptism. This is the unity we have received from God. As we recognize that all covenant members have received this common inheritance, this gives us the foundation from which to work on improving that unity. We are an embryo in the womb. To look for full governmental unity now is to look for a kid in the second trimester to grow Aaron’s beard, so that the oil can run down it, to use a grotesque image. Although I don’t have time to argue for this fully here, this is why the postmillennial vision is so important. Postmillennialism argues (on exegetical grounds) that the Church will see days of glory in the future far surpassing anything we have seen up to this point. Postmillennialism argues that the Church is in fact still an embryo, and that we will one day be a perfect man. We are not yet that perfect man. Assuming that this is God’s decree and that someday this will come to pass, then I am obligated as a faithful servant to work and labor in the direction of that decree. I want to show why this is so important for classical Protestants. Without it, there is no way to keep Protestant churches from disintegrating into a sect mentality. If God has no plan for the Church in history, then we need not have one. If there is no telos toward which we are growing, then we need not have any regard for it. In another variation of this, if the “perfect man” that the Bible talks about is manifest only in heaven, then there is no pressing need to strive toward that perfect man on earth. (See my book Heaven Misplaced for a further discussion of this.) Consequently, in my view, the error of Protestant sects is that of assuming that God has no earthly plan for the history of the institutional Church and that there is no embryo at all. What you see around you is what God wanted from the beginning, which is to say, a fragmented, scattered collection of churches. All things will be put right in heaven, they affirm, but in the meantime the earthly pandemonium is actually a design feature. But the contrary error of Rome is that of assuming the embryo is already fully grown in all essential respects. But this leads to an a priori inability to see a new historic work of the Spirit. The historic Protestant looks at the current problems and affirms that God is sovereign over all such apparent impediments. The sin will be dealt with, and some things that looked like a bad business to us will actually be revealed as having a larger divine purpose. When God wants to knit a perfect man throughout the course of a sinful, fallen world, He does so. The fact that He knows what He is doing should be apparent to us by now. But we continue to write Him off, as though His prophecies on this subject will somehow fall to the ground. This means that I believe in the eventual reunion of all covenantal communions. This extends even to the Jews, as Paul notes in Romans 11. If wild olive branches could be grafted into the cultivated tree and yet grow, what will happen when the natural branches are grafted back in? Life from the dead. The only communions that will not be grafted back into the one olive tree will be those communions that no longer exist.

Douglas Wilson,  Papa Don't Pope: Why I'm Not a Roman Catholic (and Why the Future is Protestant) .