What is the problem with religious fundamentalism? For the most part, religious extremists have the attitude that revelation=truth. For example, a radical jihadist Muslim would believe it is okay to kill people for choosing another religion besides Islam because they would say that is what the Koran says so it must be right. An agnostic or an atheist, however would say "Divine revelation? Nonsense! I don't even know if divine revelation is possible. If there is such a thing as absolute truth, then reason alone is sufficient for discovering it." This equation could be summed up as reason=truth.
A Christian, on the other hand, says, "You mean to say that a God capable of creating flowers, galaxies, peacocks and human eyeballs would not be able to reveal Himself to human beings if He actually existed? Nonsense! If God exists, divine revelation is possible."
Those who take an extreme position on both the Bible and the Koran have no difficulty in believing in divine revelation, they simply see no need to add reason to the equation for establishing a criteria for truth. The problem with this equation is that it doesn't seek to clarify which revelations are genuine and which ones are not.
The unique Christian perspective is this: revelation + reason = truth. In the New Testament, God is intrinsically bound to reason. This is the meaning behind the Greek word "Logos" which is translated "Word" in John Chapter 1. "In the beginning was the Word and the Word was with God and the Word was God." If God is the Word and the Word is reason, then anything that God does should be expected to be reasonable by any normal human beings' standards, especially if human beings are created in the image of God. This is why Jesus and the Apostle Paul appealed to human reason so often in their interactions with other human beings.
As far as I know, Christianity is the only religion or philosophy that believes that truth is grounded in revelation from a personal being (as opposed to Hinduism and Buddhism which denies God as a personal self-aware being) and then seeks to establish reason as a criteria for judging divine revelation. This is why the Apostle Paul admits that if "Christ has not risen from the dead, your faith is in vain." Whether Christianity is true or not (which of course, as an evangelist, I believe it is) one still has to admit that only Christianity subjects itself to vulnerability by establishing reason and historicity as a criteria for judging its claims.
The Bible says, "Come let us reason together." Anyone up for cappuccino?