Some factors which may affect the fertility of Muslim populations.
Many people know that Islamic scripture discourage female Muslims from marrying non-Muslims while it is generally accepted that it allows for male Muslims to marry non-Muslim women, at least those who are Christian or Jewish. The rational is that Muslim men are able to guide/control the religious development of the family so that the kids grow up Muslim. This sticks in the craw of many liberal Muslims who believe in equality and is seen by many critics of Islam as an example of a mindset of conquest (men are allowed this freedom because it will increase the number of Muslim children but women are not because it might reduce the number of Muslim offspring).
Regardless of whether it is an example of a mindset of conquest, what if it is not true? Getting real data about such things is like pulling hen’s teeth but an interview from 2003 by “Liberal Islam Network” with an Islamic professor points to some census data of Indonesian towns which seem to indicate that interfaith marriages where the woman is a Muslim have far better retention rates for children (i.e. they remain in Islam) than if the father is Muslim. And this seems to be in areas where there is a Muslim majority population. While it is unexpected, it perhaps should not be, that the faith of the mother would have a stronger influence than that of the father. This is not to say that Muslim men who marry non-Muslim women won’t have any Islamic children or that all children raised by an Islamic mother in an interfaith marriage will be committed Muslims in adulthood. But any Muslim population with a sizable intermarriage rate will need a total fertility rate that is higher than that which mere birth and death statistics would suggest. And that is without any apostasy from the children of non-interfaith marriages.
And having this one-sided approach to interfaith marriage can create another issue: a surplus of single females in the population. Despite the allowance for polygamy in Islam, the poor can rarely afford it and few of the educated (especially women) want to practice it; at least not to the degree that it can soak up the number of single women who are left when Muslim men out-marry. Whenever I hear of a case of Muslims in the West practicing polygamy it is often a case where the state is picking up the tab via welfare. Even when those women marry outside Islam and produce more Islamic kids than their interfaith male counterparts they still do not likely see the same retention rate of offspring as non-interfaith marriages produce.
An article on women in Arab countries makes some interesting claims. While we normally associate growing wealth with falling fertility rates, the regions of the Islamic world which experienced oil wealth in the 70’s and 80’s saw a situation where parts of the population became wealthy without the need for women in the workforce which created a situation where the fertility rates were kept artificially high for nations of similar wealth (just as it has been suggested that it is not the oil wealth that breeds corruption in these nations but that the existence of the wealth moves poor and corrupt states up into the company of richer nations where their level of corruption is less favorably compared. But lately the fall of oil prices (excluding the recently defunct oil boom) may be causing these nations to reignite the demographic transition that tends to occur in nations as they develop. The end of the age of high dowries which the oil wealth fueled could also be requiring women to spend more of their early years in school and, lately, the workplace. These factors might explain why the notoriously high fertility rates in Arab nations seem to be falling faster than the did for other peoples who made the demographic transition.
Oh and that female genital mutilation that many traditional Islamic cultures practice? In addition to occasionally being fatal it reduces fertility. And not just for women:
“It has been argued by many that the smaller vaginal opening left by the mutilation increased the husbands’ enjoyment. Interviews with young men in the Sudan have shown that this is not always the case. Many of them find sex with a circumcised woman painful sometimes even leading to injury and occasionally impotence. Often they would prefer to wed an uncircumcised woman but family and social pressures maintain the practice.”
A practice which makes women more likely to be infertile and makes sex painful, even causing impotence in men… and they wonder why so few Kaffurs do this to their daughters.
There is also a group that is farther behind them on the demographic transition curve: Sub-Saharan Africans. And they are retaining and embracing the Christianity. I am not a big fan of any religion but Christianity is so much more tolerable to Sharia that I am willing to allow its growth (ain’t I magnanimous?). Let it Christianity stabilize the psychological soil as it were.
Those Islamists of a triumphalist nature like to announce that the Islamic demographic increase will result in an Islamic world. I contend that they are full of (halal) baloney. Islam is Wile E. Coyote. Having run off the cliff he is just feeling the absence of ground with his toes.