Behind religious fanaticism is fear: fear that indiscriminate punishment will follow if certain “divine” laws are broken.
While it might seem that fanatics are angry when a law is disobeyed or made invalid, in actual fact, they are afraid. Because that punishment affects everyone – it is not restricted to the “guilty” but affects believers and non-believers alike, such as the catastrophic earthquake or volcanic eruption.
A fanatic is trying to help (in his/her odd way) and protect others from a far worse punishment.
Fanaticism runs on the supposition that the universe is run by a ruthless, cruel and (to paraphrase Robert Anton Wilson) clumsy dictator who sees only nails while wielding a divine hammer. Some might argue that reality is not a democracy, that this is just the way things are, that to argue divine laws would be akin to arguing against the law of gravity.
But then why is it so easy to run afoul of religious/divine commands? Why make a universe where it is so easy to anger its creator? Shouldn’t these laws be (to some degree) hard wired in our innate sense of good and evil?
For the fanatic, this indiscriminate judgement provides a sense of order to the chaotic and scary universe that surrounds them. It provides the reason why those children died, why he was cheated on, why she was passed up for a promotion. It “proves” that only with greater vigilance and adherence, such tragedies can be prevented.
But in the end it is just fear. People fear the world. They don’t understand it. They don’t know why it is the way that it is. They view things, in part, from an ahistorical viewpoint. They do not necessarily understand or are even aware of the various forces in this world, the differing viewpoints, the processes that formed to our current environment.
Can one reason with a fanatic? Yes, but one must realize that at the base of their concern is fear. Do not argue in the face of their beliefs, for they will only hold onto them more dearly. Rather, gently educate about only tangentially related items. A door might open a crack. He/She might ask some questions, but in answering, one must always be respectful of that very real fear and concern that resides within.