How do churches grow?

Last week we looked at Rodney Stark's book "The Rise of Christianity: How the Obscure, Marginal Jesus Movement Became the Dominant Religious Force in the Western World in a Few Centuries."

In it, Stark used the growth of The Church of Jesus Christ of Latter-day Saints over the past couple of centuries as his benchmark. Stark is on record as saying that the LDS Church is the only religion to arise in recent times that seems to be on track to become a major world religion.

Before we blush from the flattery, let's remember: By the time the primitive Christian church became the dominant religion of the Roman Empire, it had lost much that would later need to be restored.

The apostolic authority was gone. The doctrine of the nature of God had become nearly indistinguishable from neo-Platonism. Church officials were often careerists. Doctrinal disputes were settled, not by revelation, but by argument, politics or violence.

Yet people kept joining the church in ever-increasing numbers, regardless of the loss of authority and the politicization of church offices.

If doctrine or authority or inspiration is the main factor in conversion, why did the loss of them make no difference in the rate of conversion?

What Stark has found is that doctrine, in itself, is not the primary reason people join a new church.

My first response, as a Mormon, was to say, That's absurd. What does he think our missionaries are doing, if not teaching doctrine?

But then I realized: Whether we're baptized at age 8 or converted as an adult, we join on the basis of scant doctrinal knowledge and then spend the rest of our lives learning to understand more and more.

Those early Christian converts had the stories of Jesus and the community of the Saints. And they were welcomed into a social network of supportive people who tried to live by the teachings of Jesus.

Stark's research shows that conversion works best when it follows existing social networks — when conversion burns through whole families or existing groups.

We've found the same thing: People who have friends or relatives inside the church find the transition to church membership much easier. How many times have we been told that people who are taught the gospel in the home of a member are much more likely to join the church — and stay in it?

It's not the house or the furniture, folks, it's the friendship, the level of comfort and confidence.