Are religious people with large offspring conquering the world?

By Steffen Kröhnert and Reiner Klingholz



This paper was sponsered by the Robert Bosch Foundation.

Click here (PDF) to view the full German version of the study.


Religion has been on the retreat in Europe since the mid-20th century. While 80 per cent of the people still believed in god in most European countries around 1950, this number has declined significantly until 1990. However, on the basis of low births rates in almost every highly developed industrial country, some scientists presume that the religious population will regain numbers. Not because of a self-driven renaissance of religiosity, but due to the fact that adherents have considerably more children than atheists. The discussion paper "Faith, Power and Children" by the Berlin-Institute for Population and Development highlights this assumption.

Despite all religious differences, having more children than non-believers unifies Catholics, Protestants, Jews and Muslims. Traditionally, all large monotheist religions propagate paternalistic family values. Therefore, it’s the women’s responsibility to have children and to look after them. Men, on the other hand, are urged to protect wife and children and to provide for them materialistically. Every single large religion discourages non-reproductive behaviour as for example divorce, abortion or homosexuality. In history, religious denominations that implied these family values prospered. The transmission of your religious belief onto your, if possible, numerous offspring is a more effective form of spreading your faith than trying to proselytise people. In fact, today’s worldwide number of religious people is rising. Notably, the strong population growth in Islamic countries, where religion is of significant importance, supports this development.

However, looking at less developed countries, the correlation between growing wealth and declining number of children proves to be stronger than the one between religiosity and large number of children. The less prosperity and social security there is, the more faith in a supreme power appears to be indispensable to the people. Accordingly, many people in poorer countries believe in god. However, as more and more countries progress economically, even extremely religious societies experience a declining number of children. Medial fertility rates in classic Islamic states such as Algeria, Morocco and Turkey are just above two children per woman and even below that figure in Iran - despite the fact that for example in Turkey 75 per cent of the respondents stated that religion played an important role in their life. Only eleven per cent of Germany’s inhabitants gave that answer. The reason for population growth in most of the Islamic influenced countries cannot be found in the large numbers of children, but in the countries’ age structure, which still displays a large number of young people who just enter parental age. Overall, however, population growth in these countries will soon come to a hold.

The ten countries with the largest Muslim populations are home to two thirds of the world’s 1.57 billion Muslims. The combined population growth rate averages currently 1.68 per cent per year. Compared to a total world population growth rate of annually 1.2 per cent, this is a considerable but not dramatic surplus. Looking at Europe and the United States, where population growth stopped, amounts 0.6 per cent respectively, the difference is significant. However, people presume that population growth in almost every Islamic state - and therefore the number of adherents - will slow down gradually.

On the other hand, the population’s religiosity could increase due to childbearing in countries of the western world. Research shows that people who consider themselves religious have significantly more children than people who do not. Assuming that a distinct majority of people maintains the religiosity of their parents, this could, alongside the western world’s low fertility rate, lead to a stop of the secularisation trend or rather reverse into the opposite. Furthermore, the religiosity of immigrants and their offspring could have a share in this development. The trend appears to approve this: Since the 1990s, the religious population in numerous European countries that believes in god and life after death remained stagnant or, in fact, rose slightly.



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