In response to a post Dave made a while back.
Bear with me. In the novel Piercing the Darkness, one of the main characters, Sally, realizes that she is attempting to navigate her life based on a allegorical “map” which has no landmarks, no borders, no prominent terrain features, no paths, nor roads.
Using this map, she is unable to determine her location. She is unable to tell if she is on the right path, near the good, or near the bad. In fact she is unable to determine which direction she is headed or if her current location is even represented by the map.
The allegory relates directly to the question you ask. Many people are bothered by the vagaries of relativism, or even the breadth of moral acceptance offered by liberalism, leaving them in the same predicament as Sally above, not knowing where they are and if they are headed the direction they want to go.
Fundamentalism offers them a moral map that has boundaries, landmarks, and directions. Whether you agree with it or not it creates a structure in which to live, providing guidance to the unguided. I believe the attraction to fundamentalism is the attraction to knowing where you stand and where you are headed.