One of the core tenets of modern Latter-day Saint missionary strategy is that missionary work through members’ friends and family is much more efficient than cold-calling approaches like knocking on doors. This approach has its roots in the Rodney Stark hypothesis that religious movements largely grow through networks, and that even apparent cases of mass conversions through teaching such as the early Latter-day Saint British missions or the Day of Pentecost were probably more network-driven than they appear at first glance.
(A non-sequitur sidebar about Stark; I had the privilege of being maybe the last postdoc or graduate student who had the chance to work with Stark, although it ended up being limited to a few meetings. Also, one of the ironies of Stark’s theory is that, if I’m remembering correctly, according to Armand Mauss’ intellectual autobiography Shifting Borders and a Tattered Passport, Stark’s own parents converted to the Church through tracting, but I read the book a while ago, don’t have a copy on hand, and Google Books doesn’t appear to be allowing the search option for that book, so somebody will have to confirm).
The Church’s in-house numbers do indeed show that a discussion through a member is much more effective than a discussion from cold-calling (source, my Mission President), and for the most part I agree with the Stark hypothesis. However, all of the work on this has looked at measures of single ties, nobody has made a complete graph of network ties of an early New Religious Movement, so for a paper I wrote years ago (and will eventually get around to publishing when kids are older, etc.) I mapped out the networks of who knew who before conversion in the early Church of Jesus Christ of Latter-day Saints. (I also mapped out the the Koresh Branch Davidians, which involved interviewing one of the survivors of Waco, as well as US Unificationists, the Seekers, and the Process; I also tried to contact every 1st generation, new, small religious movement in Melton’s Encyclopedia of American Religions, and realized there aren’t as many “cults” out in the desert as popular imagination would have us believe, but here I will limit the discussion to the Church of Jesus Christ of Latter-day Saints). Additionally, I got access to a very helpful database kept by the Kirtland missionaries (with due thanks to Karl Anderson) that connected early membership records to primary source documents about conversion stories.
The listing of early members is from Platt’s 1989 article. The graph is too big to fit as an image in the body of the post, so the hyperlink is here, although the version without names is pasted above.
If I got any particulars wrong let me know, but for the most part this does provide support for the Stark hypothesis: often people come into religion in clusters. In this case, the early Church essentially consisted of the Smith/Rockwell cluster, the Whitmer cluster, the Knight cluster, and the Polly cluster, with a few isolated individuals.
However, cold-calling isn’t completely useless (long afternoons knocking doors in the hot Spanish sun notwithstanding), as it occasionally allows the establishment of beachhead nodes in other networks, which are useful when current networks have already been proselytized. For example, the Church went from being essentially a collection of a few families to a more established religious organization because Sidney Rigdon’s conversion brought in his congregation, and Sidney Rigdon was connected to the Church through Parley P. Pratt, who was an “isolated node,” a convert not previously connected to any members. (Also, of the 166 Kirtland members for which there was enough information to know whether they were introduced to the Church via cold-calling/materials or networks, about half [47%] indicated in the primary sources that they had heard about the Church through Church missionaries or materials, although in some cases the record is unclear whether they may have known other members beforehand.) So knocking on random doors does occasionally pay off in ways that working through networks doesn’t.
Organizational behavior research has suggested that with membership there’s often a recruitment/retention tradeoff. Having a lot of non-member friends allows for more missionary opportunities, but it also makes it more likely that people leave the Church (although, in the Mormon corridor context, I wonder if the fact that people who know a lot of members also know a lot of ex-members, who are forming their own particular cultures and communities in Latter-day Saint heavy areas, might obviate that retention advantage)
As much as we’d like to think the one member in their family and community can keep the faith in the middle of Timbuktu, it’s hard and community matters. On the other extreme end of this continuum are groups like the Jehovah’s Witnesses or Amish who have very intense in-group cohesion, but it comes at a cost of being able to reach into other networks because all their friends are members of the faith. With the Church we have a good mix. Some people thrive in circumstances where they’re the only member in their non-Church networks, and some people enjoy being in the Mormon Corridor, to each their own, and there are benefits to the institutional Church for both.