@dogdog,
I think you are mistaken about the cause of fundamentalism.
Aside from the people who use it as a means to enrich themselves with wealth and power, it is born of a deep and fearful insecurity rather than delusions (and certainly not delusions of grandeur).
If you can believe that God (in any form) controls everything that happens, and that certain scriptures tell you everything you need to know to insure that God smiles on you, it must provide a great sense of relief and security.
Life is no longer this chaotic mix of random happenstances which presents too many choices and too little certainty.
It's not a coincidence that a great number of fundamentalist have come to their beliefs after their lives have been turned upside down by circumstances or themselves.
If you believe (in large measure because you need to) that God will bless your life if you simply follow his instructions (as presented in scripture) then it's far too risky to try and interpret those instructions and assume that you can tell what is truth and what is myth. It's quite the opposite of a sense of self grandeur.
For most so-called
fundamentalists, their fundamentalism gets blended into the day to day requirements of living, and the questions like whether or not Adam and Eve were truly the first two humans doesn't inform their daily choices and decisions , but is only considered when the subject is brought up. When it is, they're quick to answer because for them it's an easy question:
If that's what it says in the Bible, then it is so. No point in thinking about the ramifications of it being true. We must obey the laws of God. He is not required to obey the laws of Man...including those of Science.
I strongly suspect that a great number of them have their doubts, but they keep them secret and to themselves, and they fight them even if they have to blame them on a supernatural force of evil. When given the opportunity to publicly affirm their fundamentalist trust and reliance upon God, that's what they are going to do and with gusto.
The alternative is returning to a live of fearful uncertainty where they and not God have to decide the course of their lives.
Fortunately, the great majority of self-described Christian fundamentalists in this country are essentially harmless because
a) They are not such fundamentalists as they suppose
b) The basic tenets of Christianity are pretty peaceful and align well with Society's laws
c) The people who are able to lead them on a grand scale are relatively modest in their ambitions
Of course there will be those who argue that if their fundamentalism leads them to voting against gay rights or abortion rights then they are not harmless, and I suppose if those things are very dear to one's heart, then they are not, but they are not seeking to stone homosexuals or execute mothers who have abortions or doctors who perform them.
There is, of course, a small number of fanatics who actually do advocate killing gays and abortion doctors, and for them their fundamentalism is born of delusions and quite probably delusions of grandeur, but they are the exception and not the rule.
This is not to say that I endorse fundamentalism of any religious variety, or that I don't believe that it can be a dangerous force. It can be and we shouldn't assume that it won't ever be in this country, but in the main it is not and these people are not insane.
In any case what are we to do about them? Outlaw their fundamentalist beliefs?