These last days, a mathematical study about a purported decline of religious affiliation incited various (online-)debates. It was presented by Daniel Adams, Haley Yaple and Richard Wiener at the American Physical Society meeting in Dallas. Although I was asked by a German science-portal to write an article about it and waited some more days, I couldn't find a single English-using writer pointing out the main flaw of their elegant model: Adams, Yaple and Wiener didn't include the well-tested effects of religious demography.
There are two main points to be addressed:
1. Members of religious communities tend to have (far) more children as their non-religious peers, especially among the wealthy and educated. Successful religious traditions are able to attribute value to having children "because" they may refer to superempirical agents (such as ancestors or God blessing marriage, family and specific lifestyles).
2. We know about lots of religious traditions whose members retained extremely high fertility throughout subsequent generations (i.e. the Old Order Amish, the Hutterites, orthodox Jews...). In contrast, we didn't find a single non-religious population, movement or group that was able to retain at least replacement level (2.1 children per woman) for just a single century!
A few weeks ago, Jonathan Leake from the Sunday Times put the findings into a sharp headline: "Atheists a dying breed as nature favours faithfull." The nine countries chosen by Adam, Yaple and Wiener for their ongoing secularization are actually supporting these findings: All of them are showing fertility rates below replacement level.
Another example - The Christian Quiverfull Movement in the USA
The United States of America experienced repeated cycles of secularization and religious revivals (mainly) due to religious fertility. The established standards of religious rights and liberties led to a competitive, religious-demographic marketplace with various highly fertile traditions. Among the newcomers is a bottom-up-evolving movement whose influence is already surpassing it's membership of about ten thousand heads: The Quiverfull Movement, named after the message of Psalm 127, Verse 3 to 5:
3 Sons are a heritage from the LORD,
children a reward from him.
4 Like arrows in the hands of a warrior
are sons born in one’s youth.
5 Blessed is the man
whose quiver is full of them.
They will not be put to shame
when they contend with their enemies in the gate.
A new branch of the Christian Patriarchy Movement, female and male members of the Quiverfull movement discovered large families as a costly and hard-to-fake signal of religious faith and as a way to "re-conquest" the country demoghraphically from the purported dominance of secularism, feminism and other -isms. Kathryn Joyce wrote a compelling (and critical) study about the fresh and quickly expanding tradition in "Quiverfull - Inside the Christian Patriarchy Movement".
And here is a report made by Jennifer London about the movement.
Please note that I am not endorsing any specific religious tradition nor the idea that human beings should proliferate at any cost. But as a scientist working in the field of evolutionary studies, I could not ignore the reproductive potentials of religiosity, its genetic basis and the ongoing biocultural evolution of Homo religiosus. There is a central irony to be found:
Non-religious proponents of evolutionary theory tend to bring up far more scientific arguments. But religious creationists tend to bring up far more children.
Regardless of holding religious beliefs or not, these findings are worth considering.