Second, moderate religion propagates and legitimizes the vehicles of fundamentalist ideology — both the texts and the rituals. The fact that millions upon millions of Americans believe that the Bible is a holy book drives publishers to print millions upon millions of copies every year. Bibles are available in every home and on the back of every church pew. And all it takes for a fundamentalist to be born is for one lost soul to pick up a copy and find a powerful sense of purpose in a literal interpretation of the text. The same is true of the Koran.
Ergo, if there were no moderate religion, there would be no fundamentalism. Sort of like how if there were no football games, there would be no hooliganism (I honestly can't tell if that's a serious anti-football perspective or a pinpoint-accurate parody of the anti-Islam rhetoric). Or if only the public had never been exposed to the study of biology, we would have never had a half-century of progressives being infatuated with Social Darwinism and eugenics (in case you need to be reminded that religion does not have a unique power to inspire men to commit atrocities in service to an imaginary future paradise). Or if there had never been a field of economics, there would have never been a Karl Marx to addle the brains of leftists right up to the current day.
You can use this formula to come up with any number of your own absurd counterfactuals and hypotheticals, but the important thing is, at this point, we are simply at loggerheads: you either believe the human race is capable of being perfected through education and social engineering, or you believe that no matter what, the diabolical genius of our species is that we can make a miserable mess out of absolutely anything, we will always find a way to sabotage our contentment, and therefore, it is not worth confiscating or destroying what makes nine people happy in the vain hope of teaching the tenth a lesson. If religion didn't exist, people would find another justification for murdering each other.
To give Rambow credit, he does offer a solution other than aggressively attempting to morally shame people out of religious belief. Unfortunately, that solution is to demand that moderate religions essentially perform the same surgical operation on their scriptures that Thomas Jefferson did and excise all the malignant verses that don't conform to the ethical fashions popular among modern, educated progressive sensibilities. A pretty tall order in itself, this seems reminiscent to me of the naive arguments from social conservatives claiming that if only kids weren't exposed to rock and rap lyrics glorifying sex and drugs, they would never be tempted to experiment with them. Not to mention, I don't see what's to prevent the black market allure of scriptures promising the true, unexpurgated version from attracting the lost souls Rambow fears. The genie is out of the bottle, the apple has been eaten, and violence of some sort will always be with us.