Suicide missions are not always religiously motivated, but according to Oxford University sociologist Diego Gambetta, editor of Making Sense of Suicide Missions, when religion is involved, the attackers are always Muslim. Why? The surprising answer is that Muslim suicide bombing has nothing to do with Islam or the Quran (except for two lines). It has a lot to do with sex, or, in this case, the absence of sex.
What distinguishes Islam from other major religions is that it tolerates polygyny. By allowing some men to monopolize all women and altogether excluding many men from reproductive opportunities, polygyny creates shortages of available women. If 50 percent of men have two wives each, then the other 50 percent don't get any wives at all.
So polygyny increases competitive pressure on men, especially young men of low status. It therefore increases the likelihood that young men resort to violent means to gain access to mates. By doing so, they have little to lose and much to gain compared with men who already have wives. Across all societies, polygyny makes men violent, increasing crimes such as murder and rape, even after controlling for such obvious factors as economic development, economic inequality, population density, the level of democracy, and political factors in the region.
However, polygyny itself is not a sufficient cause of suicide bombing. Societies in sub-Saharan Africa and the Caribbean are much more polygynous than the Muslim nations in the Middle East and North Africa. And they do have very high levels of violence. Sub-Saharan Africa suffers from a long history of continuous civil wars—but not suicide bombings.
The other key ingredient is the promise of 72 virgins waiting in heaven for any martyr in Islam. The prospect of exclusive access to virgins may not be so appealing to anyone who has even one mate on earth, which strict monogamy virtually guarantees. However, the prospect is quite appealing to anyone who faces the bleak reality on earth of being a complete reproductive loser.
It is the combination of polygyny and the promise of a large harem of virgins in heaven that motivates many young Muslim men to commit suicide bombings. Consistent with this explanation, all studies of suicide bombers indicate that they are significantly younger than not only the Muslim population in general but other (nonsuicidal) members of their own extreme political organizations like Hamas and Hezbollah. And nearly all suicide bombers are single.
Being a single male wondering where the women are, and remembering the younger years especially, I can understand the motivation that 72 waiting virgins might provide to a hormone-addled young man to do whatever it takes to gain access to that prize.