When the Letter to Diognetus describes the diffuse influence of Christians in the world, it uses the living imagery of the soul:
What the soul is in the body, that Christians are in the world. The soul is dispersed through all the members of the body, and Christians are scattered through all the cities of the world. The soul dwells in the body, but does not belong to the body, and Christians dwell in the world, but do not belong to the world.
Hunter Baker has more recently argued that “the church is the soul of the system.” If this is not to be understood in a clericalist sense, then it must refer to the organic church as the soul of the polis, so to speak.
Abraham Kuyper presents the organism/institute distinction in his sermon, “Rooted & Grounded,” which appears in the forthcoming anthology On the Church, part of the Abraham Kuyper Collected Works in Public Theology. Kuyper’s ecclesiology can well be understood as the crux of his public theology, and the organism/institute distinction is at the core of his conception of the church in its relation to God and the world.
In “Rooted & Grounded” Kuyper observes that both realities the distinction points to must be kept together. We have to do justice both to the dynamic, living, organic aspects of the body of Christ as well as the structural, formal, and institutional expressions of this community.
Thus, says Kuyper,
“Rooted and grounded” unites organism and institution, and where Scripture itself refuses to allow any separation, it weaves them together. By means of the person who sows and plants, the metaphor of vital growth overflows into that of the institution; by means of the living stone, the metaphor of the building flows over into that of the organism. The church of the Lord is one loaf, dough that rises according to its nature but nevertheless is kneaded with human hands and baked like bread. The church is called a multitude of priests, legitimated through birth but consecrated only through anointing. A bride brought forth by the Father but accepted by choice. A people, finally, who indeed sprouted from the living trunk but nevertheless are organized with wisdom and guided with self-motivation.
Just as body and soul are united in the human person, the church as organism and institute are united in the people of God and, ultimately, in union with Jesus Christ.