Economist and Episcopalian John Chilton has a very interesting post at Episcopal Cafe about why mainline churches have declined relative to more conservative churches. Like the true economist that he is, John looks at the data.
John notes that at one time the growth of more conservative churches was indeed due to higher fertility rates, but then observes that other factors are now more important:
The relative decline of mainline denominations could of course be due both to differences in fertility and in evangelism. My commenter pointed me to what he admitted was a somewhat dated paper here. From that tip I was able to find a more recent paper, “The Demographic Imperative in Religious Change in the United States” by Michael Hout, Andrew Greeley and Melissa J. Wilde, The American Journal of Sociology, Vol. 107, No. 2. (Sep., 2001), pp. 468-500 [JSTOR, subscription only].
Hout et al. have individual records on religious affiliation at birth, change in affiliation and fertility rates of women through 1998 via the General Social Survey. The data is recent enough to include the rise of the Religious Right in public awareness, but not to capture developments after 2003, the year that Gene Robinson was confirmed as the Bishop of New Hampshire. This is just as well because they do not report on denominations separately. The 139 Protestant denominations are classified and grouped as either mainline or conservative.Socioeconomically the conservatives have become more like the mainline denominations. They have climbed the economic ladder, but unlike in the past, they are less likely to switch to a mainline denomination.
Hout and his co-authors report, conservatives have succeeded in evangelism because they have conformed to the edict, “be fruitful and multiply.” From the GSS records they were able to tease out fertility rates for women in the cohorts born between 1903 and 1973. Using only the fertility data they then project the implied growth in membership from 1903 to 1998 – in the following categories: mainline, conservative, other religion, and no religion. Their result:
Evidence from the General Social Survey indicates that higher fertility and earlier childbearing among women from conservative denominations explains 76% of the observed trend for cohorts born between 1903 and 1973: conservative denominations have grown their own.
Again: “conservative denominations have grown their own.” Hence the “demographic imperative” – a smaller group will eventually become the larger group if its growth rate is larger. For much of the 20th century the mainline fertility by age cohort was just over two, barely enough for zero growth. In contrast, conservative fertility in the early part of the century was almost one more child per woman; more recently it remains above but is nearly equal to mainline fertility.
Why has conservative fertility declined? Socioeconomically the conservatives have become more like the mainline denominations. They have climbed the economic ladder, but unlike in the past, they are less likely to switch to a mainline denomination.
Herein lies the other substantial part of the reason the conservatives have had more success in evangelism. They not only grow more of their own, they “teach their children well” so that they do not convert to a mainline denomination in their adulthood. This is not to say that conservatives have improved on "backdoor evangelism," i.e. the rate at which members leave. Rather, most of those who leave don't join mainline denominations; they grow up to be unaffiliated with any faith.It's a great irony that after differential birthrates, the second most important fact in explaining the rise of conservative membership relative to the mainline is that a portion of conservative youth that in the past would have converted to mainline in their adulthood now drop out of Christianity altogether.
Two final findings: (1) “a recent rise in apostasy added a few percentage points to mainline decline” and (2) “conversions from mainline to conservative denominations have not changed, so they played no role in the restructuring.” The bad news for the mainline denominations is that they are losing more of their young people. (But this is only a small part of the explanation of the decline, and it could have to do with recent trends in delay of marriage, and delay in childbearing.) The surprising thing about conservative denominations is that their growth is not due to work in the mission field. It has to do with reproduction and rearing. Reports of their success in evangelism are greatly overstated.
Read it all.
This is not to say that the Episcopal Church should not focus on evangelism--this is still critically important--especially in efforts to attract younger couples back to church.