Central to Schaf’s work (The Principle of Protestantism) is the insistence that the Church as the body of Christ on the earth possesses the fullness of Christ now in no less or greater a degree than when Christ first ascended into heaven and poured out the Spirit of the Father on the Church. And at the same time, this reality is still being worked out in history. In other words, the task of the Church is to grow into and more fully develop what is already there, what has already been given in the gift of the Spirit. Of course the Spirit is the Spirit of Christ and therefore in him, the fullness of the Trinity is bestowed upon us. Yet, there is a continual working out of this reality. The Christ whom we have become one with in the Spirit must still be impressed upon us more and more. At the end, when the kingdom is delivered to the Father, and Christ is fully and obviously all in all, then this gap will be closed. The reality will have worked its way out into all of reality.
In Protestant terminology, this is the relationship between justification, sanctification, and glorification in individual soteriology. But this pattern that exists in individual Christian lives, is the same basic pattern of the Church. And this relates to all of the most significant issues of conversation between Rome and the Reformation. The place of the Scriptures and Tradition is a question of this story, the relationship between sanctification and justification. The Reformers have always insisted that at the moment of regeneration, the fullness of salvation is bestowed. The gift of the Holy Spirit is the action of God giving himself. Participation in the Triune Life is Eden restored, forgiveness of sins, a righteous standing before God, and the joy of eternal life. At the same time, this reality must be worked out in time. The holiness, justice, and grace of justification must be impressed upon the entire life of a believer, until no gap remains, until the reality becomes reality (glorification).
So similarly, the Church too has been given the gift of the Holy Spirit. Pentecost was the justification of the Church as a whole. Against her, the gates of Hades will not prevail come what may. Yet, the Spirit was poured out in order to build up the Church, to equip the saints for ministry, to fit the saints together until they have formed the one new man in Christ, until the gospel has filled the earth, until all the enemies of God have been made the footstool of Christ. This is the sanctification of the Church, the growing up of the Church, the continual reformation of the Church. This is the principle of protestantism, as Schaf sees it. It is the principle of working out the reality of salvation, the reality of the kingdom in every area of life.
The challenge is always to avoid the extremes of either stagnation, assuming that what has been given is the end of the story, or revolution, forsaking what has been given in the name of “growth.” On the one hand, some think thirteen was a great age or maybe sixteen, and they are trying to stay there. Maybe we even liken it to a medical condition where someone’s body stops growing. On the other hand, others really like the tumor that is growing out of the side of their head and don’t want to operate. Both are highly problematic conditions. And Schaf wants to argue for a catholic continuity while insisting that the Church must grow up. But of course it must grow up into Christ, who is already present in the Church by the Spirit in reality. The reality must put on reality. Christ must put on Christ. The Body of Christ must become what she is.