We already know that there is a vicious strain of fundamentalist Islam that turns to violence in an effort to impose its views.
In India, fundamentalist Hindus have attacked those of other faiths, including Christians.
In the last few days, we have seen violence from fundamentalist Jews, for example in one case an orthodox man stabbing people at the gay Pride parade in Jerusalem, and in another, burning to death a Palastinian child in a protest over illegal settlements.
Christian fundamentalists are also violent. In this country, abortion-related murders of and bombings are associated with explicitly Christian extremists. Some Christian pastors have called for death for LGBT people. And a recent article in Salon points out that Christian reconstructionism is inherently violent, anti-woman, and pro-slavery. Recently, Christian conservatives have advocated calling in the national guard against legal processes they don't like, like abortion or same sex marriage (and if that's not government tyranny, what is?)
What is it about fundamentalists of all flavors, who see violence against others as justifiable?