Islam spread through the Christian world via the bedroom

Unions between Muslims and non-Muslims played a huge part in the expansion of Islam.

A Pakistani Muslim prays at an illuminated mosque in connection with Eid-e-Milad-un-Nabi, the birthday of Prophet Mohammad, in Karachi on November 20, 2018. Photo: ASIF HASSAN/AFP/Getty Images

There are few transformations in world history more profound than the conversion of the peoples of the Middle East to Islam. Starting in the early Middle Ages, the process stretched across centuries and was influenced by factors as varied as conquest, diplomacy, conviction, self-interest and coercion. There is one factor, however, that is largely forgotten but which played a fundamental role in the emergence of a distinctively Islamic society: mixed unions between Muslims and non-Muslims.


For much of the early Islamic period, the mingling of Muslims and non-Muslims was largely predicated on a basic imbalance of power: Muslims formed an elite ruling minority, which tended to exploit the resources of the conquered peoples – reproductive and otherwise – to grow in size and put down roots within local populations. Seen in this light, forced conversion was far less a factor in long-term religious change than practices such as intermarriage and concubinage.

The rules governing religiously mixed families crystallised fairly early, at least on the Muslim side. The Quran allows Muslim men to marry up to four women, including 'People of the Book', that is, Jews and Christians. Muslim women, however, were not permitted to marry non-Muslim men and, judging from the historical evidence, this prohibition seems to have stuck. Underlying the injunction was the understanding that marriage was a form of female enslavement: if a woman was bound to her husband as a slave is to her master, she could not be subordinate to an infidel.

Outside of marriage, the conquests of the seventh and eighth centuries saw massive numbers of slaves captured across North Africa, the Middle East and Central Asia. Female slaves of non-Muslim origin, at least, were often pressed into the sexual service of their Muslim masters, and many of these relationships produced children.

Since Muslim men were free to keep as many slaves as they wished, sex with Jewish and Christian women was considered licit, while sex with Zoroastrians and others outside the 'People of the Book' was technically forbidden. After all, they were regarded as pagans, lacking a valid divine scripture that was equivalent to the Torah or the Gospel. But since so many slaves in the early period came from these 'forbidden' communities, Muslim jurists developed convenient workarounds. Some writers of the ninth century, for example, argued that Zoroastrian women could be induced or even forced to convert, and thus become available for sex.

Whether issued via marriage or slavery, the children of religiously mixed unions were automatically considered Muslims. Sometimes Jewish or Christian men converted after already having started families: if their conversions occurred before their children attained the age of legal majority – seven or 10, depending on the school of Islamic law – they had to follow their fathers' faith. If the conversions occurred after, the children were free to choose. Even as fathers and children changed religion, mothers could continue as Jews and Christians, as was their right under Sharia law.


Mixed marriage and concubinage allowed Muslims – who constituted a tiny percentage of the population at the start of Islamic history – to quickly integrate with their subjects, legitimising their rule over newly conquered territories, and helping them grow in number. It also ensured that non-Muslim religions would quickly disappear from family trees. Indeed, given the rules governing the religious identity of children, mixed kinship groups probably lasted no longer than a generation or two. It was precisely this prospect of disappearing that prompted non-Muslim leaders – Jewish rabbis, Christian bishops and Zoroastrian priests – to inveigh against mixed marriage and codify laws aimed at discouraging it. Because Muslims were members of the elite, who enjoyed greater access to economic resources than non-Muslims, their fertility rates were probably higher.

Of course, theory and reality did not always line up, and religiously mixed families sometimes flouted the rules set by jurists. One of the richest bodies of evidence for such families are the biographies of Christian martyrs from the early Islamic period, a little-known group who constitute the subject of my book, Christian Martyrs under Islam (2018). Many of these martyrs were executed for crimes such as apostasy and blasphemy, and not a small number of them came from religiously mixed unions.

A good example is Bacchus, a martyr killed in Palestine in 786 – about 150 years after the death of the Prophet Muhammad. Bacchus, whose biography was recorded in Greek, was born into a Christian family, but his father at some point converted to Islam, thereby changing his children's status, too. This greatly distressed Bacchus's mother, who prayed for her husband's return, and in the meantime, seems to have exposed her Muslim children to Christian practices. Eventually, the father died, freeing Bacchus to become a Christian. He was then baptised and tonsured as a monk, enraging certain Muslim relatives who had him arrested and killed.

Similar examples come from Córdoba, the capital of Islamic Spain, where a group of 48 Christians were martyred between 850 and 859, and commemorated in a corpus of Latin texts. Several of the Córdoba martyrs were born into religiously mixed families, but with an interesting twist: a number of them lived publicly as Muslims but practised Christianity in secret. In most instances, this seems to have been done without the knowledge of their Muslim fathers, but in one unique case of two sisters, it allegedly occurred with the father's consent. The idea that one would have a public legal identity as a Muslim but a private spiritual identity as a Christian produced a unique subculture of 'crypto-Christianity' in Córdoba. This seems to have spanned generations, fuelled by the tendency of some 'crypto-Christians' to seek out and marry others like them.

In the modern Middle East, intermarriage has become uncommon. One reason for this is the long-term success of Islamisation, such that there are simply fewer Jews and Christians around to marry. Another reason is that those Jewish and Christian communities that do exist today have survived partly by living in homogeneous environments without Muslims, or by establishing communal norms that strongly penalise marrying out. In contrast to today's world, where the frontiers between communities can be sealed, the medieval Middle East was a world of surprisingly porous borders, especially when it came to the bedroom.

Christian Martyrs under Islam: Religious Violence and the Making of the Muslim World by Christian C Sahner is published via Princeton University Press.Aeon counter – do not remove

Christian C Sahner

This article was originally published at Aeon and has been republished under Creative Commons.

A still from the film "We Became Fragments" by Luisa Conlon , Lacy Roberts and Hanna Miller, part of the Global Oneness Project library.

Photo: Luisa Conlon , Lacy Roberts and Hanna Miller / Global Oneness Project
Sponsored by Charles Koch Foundation
  • Stories are at the heart of learning, writes Cleary Vaughan-Lee, Executive Director for the Global Oneness Project. They have always challenged us to think beyond ourselves, expanding our experience and revealing deep truths.
  • Vaughan-Lee explains 6 ways that storytelling can foster empathy and deliver powerful learning experiences.
  • Global Oneness Project is a free library of stories—containing short documentaries, photo essays, and essays—that each contain a companion lesson plan and learning activities for students so they can expand their experience of the world.
Keep reading Show less

What the world will look like in the year 250,002,018

This is what the world will look like, 250 million years from now

On Pangaea Proxima, Lagos will be north of New York, and Cape Town close to Mexico City
Surprising Science

To us humans, the shape and location of oceans and continents seems fixed. But that's only because our lives are so short.

Keep reading Show less

Why we must teach students to solve big problems

The future of education and work will rely on teaching students deeper problem-solving skills.

Future of Learning
  • Asking kids 'What do you want to be when you grow up?' is a question that used to make sense, says Jaime Casap. But it not longer does; the nature of automation and artificial intelligence means future jobs are likely to shift and reform many times over.
  • Instead, educators should foster a culture of problem solving. Ask children: What problem do you want to solve? And what talents or passions do you have that can be the avenues by which you solve it?
  • "[T]he future of education starts on Monday and then Tuesday and then Wednesday and it's constant and consistent and it's always growing, always improving, and if we create that culture I think that would bring us a long way," Casap says.
Keep reading Show less

Allosaurus dabbled in cannibalism according to new fossil evidence

These Jurassic predators resorted to cannibalism when hit with hard times, according to a deliciously rare discovery.

Fig 3. Shed lateral tooth of Allosaurus sp. (MWC 5011) found at the Mygatt-Moore Quarry, white arrow indicates the distal denticles.

Stephanie K. Drumheller et.al
Surprising Science
  • Rare fossil evidence of dinosaur cannibalism among the Allosaurus has been discovered.
  • Scientists analyzed dinosaur bones found in the Mygatt-Moore Quarry in western Colorado, paying special attention to bite marks that were present on 2,368 of the bones.
  • It's likely that the predatory carnivore only ate their already-dead peers during times when resources were scarce.
Keep reading Show less
Scroll down to load more…