The source is Avery Dulles' Models of the Church. This stuff has such practical implications. Let me recook it in the way of a practically oriented Seminary. Most churches mindlessly fall into one of these categories. Let me emphasize the "mindless" part. We just assume one of these is the right way.
With Dulles, I would argue that nearly all of these are an essential part of the Church. I would say also, though, that I am comfortable with the idea that some churches, like the body of Christ, may legitimately focus on some more than others.
1. The Herald
Evangelical churches often seem to mindlessly assume that the purpose of the Church is just about converting people and preaching stuff. That is certainly part of what the Church is about. And it's fine for there to be many churches that focus on this. It just isn't the whole of what a church is.
2. The Servant
Some churches focus on helping others. This is also an essential feature of the Church, although we question whether it is the only thing an individual church should be doing.
3. The Institution
Dulles rightly questions whether a church can just be institution and truly be part of the Church. I agree. You could focus on one of the others, be a bit out of balance, but still be part of the Church. But if all you are is institution, you're church probably isn't part of the Church.
On the other hand, without some structure, without some ordering to the community of faith, you're like a body without a skeleton and probably won't have much impact, especially long term.
4. The Fellowship
Some churches mostly focus on the life of the community that is already there. Call it an inward discipleship focus (although the current version of Dulles has added the discipling church as another model--I prefer to keep the original five). Call it a body life focus. It is an essential feature of the Church. In the long term, however, a church that is only focused on itself is likely to dwindle and die. There are exceptions, I suppose.
5. The Means of Grace
Some churches see the church as a means by which God brings his grace to bear on people. On the one hand, we might first think of churches that focus on sacraments. On the other hand, you might actually broaden your sense of sacrament to include all the other models:
- The Church helps facilitate God's converting grace by proclamation as a herald (the first mark of the Church--proclaiming the word).
- The Church helps facilitate God's prevenient grace by its service to those in need.
- The Church is an institution because it's hard to facilitate anything without structure (the third mark of the Church--a community rightly ordered).
- The Church helps facilitate growth in grace by fellowship and discipleship within the church walls.
- The Church facilitates the sacraments, broadly conceived (the second mark of the church).