I don’t remember when I first ran into Paul Hiebert’s idea of contrasting bounded sets and centered sets in our understanding of evangelism. It was either shortly before I finished seminary or shortly after, making sometime in the late 1980s. By then Hiebert’s work had already been in circulation for ten years, so I was far from an early adopter. I did find the imagery very helpful, primarily because it brought considerations of time into the the picture.

Dave Schmelzer, leader of the Cambridge, Massachusetts Vineyard Church, has further popularized centered set thinking in his book and blog, Not the Religious Type.

When we understand Christian conversion in terms of a bounded set, the idea is that you are a Christian if you are within particular boundary lines. The job of the evangelist, then, is to get people across those lines. Once inside those lines, you are a Christian. As long as you remain outside the lines, however, you are not a Christian.

The strength of this bounded set model is its clarity and simplicity. If you understand the boundary lines and where a person is in relation to those boundary lines, then mapping becomes easy.

The weakness of the model is that the boundary lines are often drawn arbitrarily. Different Christian groups also tend to draw them differently. Not a member of our church? Well, you’re outside the boundary lines. Is your hair too long – or too short? You’re outside the boundary lines. Not a premillennial pretrib rapturist in your eschatology? You’re outside the boundary lines. Not in favor of a particular political scheme? Well, you’re outside too. Sometimes the boundaries were drawn minimally, sometimes maximally, sometimes more informed by culture than by theology.

The centered set approach is different. Instead of asking where a person is in relation to the boundaries, this model has us asking how the trajectory of a person’s life bears toward the center of the set. In thinking of conversion to Christ, conversion happens when a person’s life trajectory becomes oriented toward Jesus, the center.

The centered set model’s strength is that it can account for great differences from believer to believer. Sometimes these differences will be cultural, sometimes theological, sometimes a matter of spiritual maturity.

http://www.solarila.com/wp-content/uploads/2009/06/bounded-centered-diagram1.jpg

In the bounded set model all you have to do to determine whether a person is a Christian is see where they plot on the map. If they are within the boundaries, they are in, they are Christians. In the centered set model it might be the case that someone who appears close to the center of the map, i.e., close to Jesus, in a snapshot plot, is actually not a Christian. Culturally they may be close – a church member, even a pastor. But over time the trajectory of their life takes them away from Jesus. At the same time someone who in a snapshot plot is far from Jesus might, if time were taken into account, be found to be drawing nearer to Jesus. The key difference here is that in the bounded set model, a snapshot is perfectly adequate to tell whether a person is a Christian, while in the centered set model a snapshot is never adequate, since a snapshot is unable to depict motion.

I have found centered set thinking to be very useful. I use it regularly in my preaching, getting volunteers from the congregation to come up front and act it out. One person is Jesus, and a couple of other people are scattered around the room. I show how a person can be close to Jesus – perhaps in terms of culture or church membership – yet be living a life that takes him farther from Jesus. I can also show how a person who might be completely across the room from Jesus – culturally and ecclesially distant – can have a life oriented toward Jesus and be on a trajectory toward him.

Sometimes I hear people lifting up the centered set model, praising it for the vagueness it allows. Instead of the clarity we hear from bounded set people (this person is in, that person is out), centered set thinking allows for more ambiguity. In the latter model we cannot tell at a glance whether a person is in or not. I understand this thinking, but don’t find it persuasive.

First, is there such a thing as being “in?” Sure, in the bounded set model being “in” is important. But it’s easy for questions of “in-ness” to lapse into cultural categories, which further lapse into questions of, “Is this person sufficiently like me?”

Clearly “in” language fits most naturally with the bounded set model. But the thing is that the centered set model can be pictured in bounded set terms. While picturing a centered set is possible to do in a bounded set, information is always lost. We pick one part of the data present in the centered set depiction and map it as a bounded set. We might chose the data point to be something like “oriented toward Christ.” When we look at a centered set picture with people represented as arrows showing their trajectory toward one place or another, that place to which they are oriented can be Christ. When we reduce the centered set to the bounded set on these terms, those who are in are those who are oriented toward Christ. A centered set depiction does give us more data than a bounded set depiction, but there is an overlap in the data.

Second, we can ask whether this bit of data is of any value or importance. Is it worthwhile for a person to know where her life is in relation to Christ? Can it ever be of value to a person to know where her friend is in relation to Christ?

In my experience, some churches don’t care about this data. Some churches don’t care because they have a universalist ethos. God’s love and grace are irresistible, so everyone will be in in the end. No one has to worry about her status, and no one has to worry about the status of her loved ones or friends. Other churches work on the assumption that no one in the current audience is in, so always do basic evangelism work with everyone on every occasion.

If the centered set model gets things at least partially correct, however, then paying heed to all of its data can be of use.

Consider Jesus’ ministry. Jesus did not minister to all people in the same way. He ministered to the crowds one way, to his opponents another way. Among his followers he ministered the larger group of disciples one way, and to the twelve another. Even among the twelve he had a special relationship with three. Jesus’ ministry presupposed that there was such a thing as coming to faith, growing in faith, and being faithful. The centered set model mirrors this practice by allowing us to visualize orientation toward Jesus (having faith in Jesus) and closeness to Jesus (growing in faith/faithfulness).

If we could improve the centered set model, however, we could add another element of dynamism. Where the bounded set model is static – you’re either in or out – the centered set model is dynamic. One’s life is in motion in some direction, and one is currently at some distance from Jesus. But how might we show another important piece of data, i.e., how one’s trajectory is changing? The arrows that are now pointing toward Jesus in the diagram, were not always pointing toward Jesus. At some point, those lives were oriented away from Jesus, but have turned toward him. When I use the model in preaching, I describe the turning away from whatever other thing one’s life was oriented toward as repentance, and the turning toward Jesus as faith.

Perhaps the lesson is that each of these models has a use. In spite of this usefulness, however, we should never take our models as completely adequate when we seek to understand a complex, dynamic reality. In fact, we will likely be better off if we employ multiple models at the same time.