The study said that secularists have tended to have fewer children since the 19th century

Secularism will decline worldwide while religion grows, according to a new study in the journal Evolutionary Psychological Science.

The study, reported in The Times, observed more than 4,000 students in Malaysia and the United States over a period of time, and found that the more religious they were, the more children they would end up having.

According to the researchers, the proportion of secularists in the world population will “slowly diminish”, while the number of religious believers will rise.

The chief reason, the study concluded, was that ever since the 19th century, the non-religious have been much more likely to use contraception. The authors wrote: “It is ironical that effective birth control methods were developed primarily by secularists, and that these methods are serving to slowly diminish the proportional representation of secularists in forthcoming generations.”

The authors defend what they call a “contra-secularisation hypothesis”, meaning that secularism will decline “throughout the remainder of the 21st century, including Europe and other industrial societies.”

The Pew Foundation has projected that the proportion of “religiously unaffiliated” people in the world population will decline from 16% today to 13% by 2050.