A number of readers have asked what I mean when I refer to U1s or U5s. This terminology makes up the "Rainer Scale" which I use to classifiy the unchurched according to how receptive they are to the Gospel. For instance, U1s are the most receptive group, while U5s are the least receptive.

I thought it might be a good idea to revisit these groups and give readers a brief explanation of the people they represent. We base the numbers of each group on our estimates that there are 160 million unchurched people in the United States.

U5 — The smallest of the unchurched population at 5 percent of the total, or approximately 8 million people. These men and women tend to be antagonistic toward the church and the gospel. Their resistance to spiritual issues is high. They are highly unlikely to come to church if invited, and they can become offensive toward a Christian.

U4 — The third smallest of the unchurched population at 21 percent of the total, or approximately 34 million people. Though this group is the second most resistant to the gospel, they are usually not antagonistic. This group may be willing to try a church by attending a special event produced by the church.

U3 — The largest unchurched group, comprising 36 percent of the unchurched population, or approximately 58 million people. These unchurched men and women appear to be neutral toward the gospel, though the reality is that they are probably leaning toward either U4 or U2. They are somewhat likely to attend church if invited.

U2 — The U2s account for 27 percent of the unchurched population, or approximately 43 million people. This group really shows signs of receptivity to the gospel and is likely to attend church if invited.

U1 — The most receptive unchurched group to the gospel. They account for 11 percent of the unchurched population, or approximately 18 million people. Many in this group are ready to receive Christ, and are anxious to hear from a Christian.