Most reasonably educated Americans are familiar with the term "Fundamentalism" as that term us used American religious discourse. Historically it came into popular use around the term of the 20th to  describe a reaction to liberalism in religious thinking associated with what was called "the higher criticism." This "criticism" turned a searching eye on the Biblical texts to see which were actual facts and occurencres as opposed to later, not always 'history,' in the sense of actual events or sayings.

The "fundamentalists," centered at first around Princeton University, rejected this "higher criticism" and drew up a list of  5 'fundamentals' which they claimed were absolutely essential to Christianity, indeed the very ;sine qua non' of the faith without which Christianity had no real eternal truth. In sum, the fundamentalist position was that the Bible was divinely inspired and was  thus inerrant, that us without error in theology or fact.  This inerrancy is still held by millions of  Americans. This book with no errors might not be so troublesome if its perfection were confined to theological matters, but when expanded to history and science, the results become grotesque.

The problem with any type of fundamentalism is that it reeks of  certainty. There is only one truth; all deviation from the 'fundamentals.' is, almost by definition, error ,if not outright evil, in religion and social thought.

Science, on the other hand, does not speak of certainty but probability. We call evolution in the natural world  a theory, but as a theory with such a high degree of certainty that we slip into calling it a 'fact.' But if we say the evolving of species in a certain way is hard fact then we gave closed the door the further, if any, refinements of the basic theory. "Facts" cannot change. "Theories" leave the door open to further discoveries.

Now today we have three theories, accepted by many facts and thus not challengable , that are creating problems that are impeding the advance of knowledge. First is religious fundamentalism , the idea that certain writings Biblical cannot be subject to error; then political Islam, the belief that major parts of Islam must be force upon the rest of the world by force if necessary. and third,  what I will call 'sexual fundamentalism,' doctrines about the sexual relationship of humans which, still day, cause major mischief in the lives and well being and happiness of millions.