In Iraq, we are witnessing yet again the tremendous harm caused by religious fanaticism. One interesting aspect of the present conflict is that it largely pits Muslim against Muslim, with some fanatics in the Sunni tradition battling devoted adherents of the Shia tradition. Both traditions, of course, rely on the Quran as the ultimate authoritative text. So why the conflict?

Well, why not? History has witnessed many conflicts between religious groups who purport to rely on the same authoritative text. For the most part, different sects of Christians no longer kill each other, but the bloodshed between Protestants and Catholics only dribbled to a halt in the early nineteenth century -- that is, apart from Northern Ireland.

And this phenomenon should not be surprising. In fact, the phenomenon of intra-religious strife highlights the key problem with using religious texts and doctrines to address ethical issues in general, and in particular, how we treat other human beings. All holy texts, and the doctrines derived from such texts, are infinitely malleable. Which is another way of saying that, in themselves, they are useless as ethical guides. The Bible and the Quran represent a hodgepodge of thoughts and observations and, in the case of the Bible, a hodgepodge of thoughts and observations extending over centuries of time. Believers who want to advocate a particular position can cherry-pick whatever scriptural passage or snippet of doctrine they find useful for making their point. If the apparent literal meaning of the text does not quite fit the position, no problem! They can make it fit by giving the text a "symbolic" interpretation or appealing to "context." Think of any position you want. You can pick some passage in the Bible or Quran to support it.

Do I exaggerate? I don't think so. Just consider a few of the various issues on which Christians have taken opposing views based on their dueling interpretations of scripture: slavery, women's rights, desegregation, capital punishment, contraception, same-sex marriage -- and on and on.

Similarly, in less tolerant times, scriptural passages were used by Christians to justify their mutual slaughter. The pope was identified (and still is by some fundamentalists) as the Beast in the Book of Revelation and chapter 13 of Deuteronomy and isolated New Testament passages (see 1 Cor. 5: 9-13) provided ample justification for the Catholic Church to extirpate Protestant heretics.

Moreover, it was not some sudden realization that "Wow, we have been interpreting these biblical passages all wrong," that stopped Catholics from killing Protestants and vice-versa. No, there were two reasons, one derived from practical considerations, the other from secular ethics. As a practical matter, by the late seventeenth century, it was apparent that neither Catholicism nor Protestantism could swipe the other away through the sword. More importantly, certainly in the long run, Enlightenment philosophy, and with it the view that all humans have a right to certain fundamental freedoms, including freedom of conscience, slowly began to have an influence. This was a secular philosophy and it gave birth to the first secular state, namely the United States.

In a secular state, religion is supposed to remain a private matter, without any role in determining public policy. But just as religion has no role in government, government has no role in religious affairs, letting individuals decide for themselves what to believe, without any compulsion, pressure, or oversight by the state. Secularism hasn't been implemented perfectly -- in the United States, for example, there's still far too much influence of religion on public policy -- but overall the track record of secular states has been very good in preserving religious peace.

There's been much debate over whether Islam lends itself to religious strife more than other religions, principally because multiple passages in the Quran can be interpreted as exhorting believers to wage holy war against unbelievers, which, of course, can include those deviants who say they're Muslims but really aren't. However, the vast majority of modern Muslims are not extremists and reject religious violence. They might point to different passages in the Quran that seem to urge peace and also prohibit killing except in self-defense.

The reality is that although Islamic extremists do currently pose more of a problem for the world than other religious extremists, the Quran is intrinsically no more belligerent than any other holy book -- nor is it more irenic. Any holy book can be read to justify or condemn violence depending on its interpretation, and there's no objective way to decide between differing interpretations.

One indisputable reason why religiously inspired violence remains more of a problem for the Islamic world is that most Islamic countries have never embraced secularism. They don't have an ethics of natural rights based on secular considerations. They have not yet been driven to the secular solution that European and Western countries embraced after so much Christian blood was spilled in absurd disputes over transubstantiation, papal authority, and so on.

In other words, they have not yet learned that it's a fool's game to try to argue against religious violence that is justified by appeal to scripture by appealing to scripture. Religion doesn't have the intellectual resources to deal with religiously inspired violence. To address religious violence, one must embrace secularism. One needs to think outside The Book.