The latest violent video game, Left Behind, is designed just for Christians--a popular Christmas gift. The goal is to convert as many non-Christians as you can and then to murder all the ones you can't. Kind of a cross between the Spanish Inquisition and a Cossack pogrom. The game is based on the psychotic ravings of the author of the Book of Revelation. One has to admire the creativity of fundamentalists when it comes to finding new outlets for their hate speech. Christian groups praised the game as one "Mom and Dad can actually play with Junior". Maybe they can even give Junior tips on the most effective murder weapons.
Some naïve folks are upset that this game goes against the precepts of tolerance and pacifism and reverence for life that Jesus preached, but most self-designated Christians seem to have found ways to spin the doctrine that allows them to be as belligerent, violent, intolerant, and murderous as Herod himself. In my personal experience (and I was raised Christian) it's easier to find an atheist practicing the teachings of Jesus than a Christian.
A group calling themselves Real Men For Jesus argue that Jesus wasn't really the Bleeding Heart liberal he pretended to be, because after all he went around overturning tables, and was belligerent and destructive and made messes for other people to clean up, just like a macho man is supposed to do--just like George Bush, for example.
In my experience, ideologues--especially religious fanatics--get violent when they're confronted with a truth they can neither accept nor refute. You don't have to make threatening phone calls, or beat up people, or lock up peaceful dissidents, or 'disappear' them, unless you know they're right.
Generally speaking, there are two factors that tend to make a religious tradition violent. The first is proselytizing--the more actively the religion seeks to gain adherents the more violent they tend to be. The second factor is related to the first: the more the religious tradition demands that its adherents believe in extremely implausible stories the more violent it will tend to be.
The relationship is clear: if in order to have an afterlife--and even better, a happy one--I have to believe in the absolute truth of what looks like a preposterous fairy tale, it will be easier to manage if I can get a whole lot of other people to buy the same story. The more of us there are believing it, the more likely it will seem to be true. This is why cults tend to isolate themselves--there may only be a few of them, but they never hear a divergent opinion.
By the same token, the more we hear of people disbelieving our fairy tale, the more anxious it makes us and the more we want to kill them.
The tension is multiplied when the stories are collected and written down in sacred texts, like the Torah, the Bible, and the Koran, full of anachronisms, barbaric traditions, primitive beliefs, and contradictions, making it both harder to believe in them and therefore more necessary to attack those who don't.
Christianity and Islam are the most violent religions in history. Islam preaches it--against infidels, at least--Christianity pretends not to, although its history--the Crusades, the Inquisition, the religious wars between Catholics and Protestants--suggests that torture, murder, and genocide are an inherent part of its ethos. But it's difficult to find a religious tradition that isn't deeply steeped in violence. Judaism was non-violent when it wasn't embodied in a state, but Biblical leaders like Joshua, Saul, David, Simeon and Levi would be tried in The Hague today for war crimes.
A life without spirituality of any kind is a life lived in a closed box. But humanity will only free itself from sectarian violence when it develops a spiritual tradition that doesn't depend on, or demand, belief in absurd tales. The Dalai Lama once said that if science contradicted sacred Tibetan texts, the texts should be modified. It would be nice if such an enlightened attitude could appear among Christians and Muslims. If we can outgrow Santa, the Easter Bunny, and the Tooth Fairy, we ought to be able to outgrow these primitive religious traditions that are tearing the world apart.