The Religious Will Inherit the Earth by Peter West

Usually about this time of the year, at Easter, I write something which some readers perceive as anti-Christian, and everybody gets stuck into me. See if this article offends anyone (well, maybe atheists).
An article, L. Ellis (et al.), “The Future of Secularism : A Biologically Informed Theory Supplemented with Cross-Cultural Evidence,” Evolutionary Psychological Science, March 8, 2017, argues that secularism is basically doomed. Secular people generally use contraception more, being geared towards material satisfaction, and thus have less children. Feminists are a good example of this.
The paper offers three testable hypotheses about the future of secularism:

Prediction 1: For humanity as a whole, religiosity will increase. This forecast is not simply due to the positive correlation between religiosity and fertility. While the pace at which this prediction unfolds will no doubt vary considerably from country to country, we expect that it will be easily detected in all countries with reliable baseline data by the end of this century.

Prediction 2: Due to the fact that Muslims have the highest reproduction rates of all major religions and are the most religious, Islam will encompass increasing proportions of the world’s religious community. Currently, about one fifth of all humans are Muslim. By the end of the current century, Islam will have surpassed Christianity as the world’s largest religion and will comprise over one fourth of all the persons on earth. In addition to Muslims having the highest reproduction rates, Islam retains membership unusually well due in part to harsh sanctions imposed for members renouncing Islam (Pierce 2004).

Prediction 3: As religiosity increases over the ensuing decades, average intelligence will gradually decline. This IQ decline should be most pronounced in countries where IQ is currently relatively high and religiosity is relatively low due partly to the inverse correlation between religiosity and intelligence. An additional contributor to a worldwide decline in IQ is that highly religious people (with high reproduction rates, particularly Muslims) should continue to migrate from their native countries to ones with below-replacement fertility, thereby supplying low religious countries with new citizens who are highly religious. By the end of the twenty-first century, we predict that nearly all of the countries with the highest proportions of secularism will become much more religious in proportional terms and observably lower in average intelligence.

Thus, people in the future will be more religious, but they also will be dumber. I suppose, given the disaster that egg head smarts have brought to society that may not be all bad: https://medium.com/incerto/the-intellectual-yet-idiot-13211e2d0577.