Philosopher Tibor Machan argues

that it's not the nature of the believer when it comes to fundamentalism, it's the truth of the belief.

Fundamentalisms, True and False

“Free market fundamentalist” is a term of abuse, intimating something badbut not showing it, thus exhibiting no respect for civilized discourse andthe human mind. And there is a way to deal with such moves—namely, to callthem what they are, verbal tricks. Although deployed by well positionedintellectuals, they reveal a desperation about lacking a solid argumentagainst the position being attacked. This is surely not a surprise.

Over the last several centuries the old faith in force of arms as themeans by which to solve human social problems has been waning. People,despite the efforts to many of the intellectuals who love the state and statist measures, have come to respect free institutions.
...
Well, old habits are hard to shed—for centuries and centuries most humanbeings were dealt with as wards of the state and only in America didofficialdom actually suggest giving up the idea. What is needed to counterthe bad habit of statism is, yes, free market fundamentalism—theuncompromising belief that free men and women, who renounce the use ofcoercive force, are doing the right thing. (Just think of abolitionism asa comparable fundamentalism.) This fundamentalism is well grounded in muchof philosophy, history, psychology, economics and practical life. It needsto be affirmed proudly and the suggestion that it is something lacking insophistication needs to be firmly swept aside.