Warning - likely to be a long - and complicated - and personal - Post.
1. By "religious fundamentalism", I mean a belief system based on a set of writings by or inspired by a Supreme Being, and which generally accepts those writings to express the literal truth about events that have occurred, and/or will occur, and about how we should behave.
2. My only knowledge of "religious fundamentalism" is of the Jewish, Christian, and Islamic variety. I do not know anything about anything like Buddhist Fundamentalism, or, indeed, whether it exists at all.
Problem No. 1 - a fundamental difference about what knowledge is "valid", and about how God's will is revealed (if at all) to people
The New Testament was written almost 2000 years ago; the Old Testament is (obviously) older. Even the Quran is more than 1000 years old. Fundamentalists of all religions appear to believe that what is written in their respective Holy Books is true, even if it appears to be contradicted by information that comes to our collective attention after those books were written.
Sorry, I just do not think that that is how knowledge works. Assuming there is a God, I believe that He or She (or It) created Man (and Woman) (or their evolutionary ancestors) with either brains or the possibility of developing brains. These brains (part of God's plan) allow us, both collectively and individually, to observe, think and learn. Thus, we are designed to be able to absorb, evaluate and act on new knowledge. This knowledge may be "scientific", that is about the world around us, or it may be about how we should act, or about anything else. New knowledge has helped us do all sorts of things, both good and bad, including build railroads, successfully treat (or even wipe out) certain diseases, and live longer. It has also let us develop the concept (or understand the previous existence of) a Universal God, who wants people to act in certain ways. It has also led us to social ideas like charity, and (more recently) the "wrongfulness" of slavery.
I suspect that at least some Fundamentalists would counter my belief with the story of Adam and Eve, who lived in the paradise of Eden until tempted into the sin of eating the fruit of the Tree of Knowledge, and that my entire approach wrongfully elevates (indeed, venerates) knowledge. The assumption of the Fundamentalists is that God knew everything when He or She wrote or inspired whatever Holy Book is in question, and that we, the children of God, should just make sure we both believe in and do what we were told. Certainly, this is a central theme in the Binding of Isaac story, where God tells Abraham to sacrifice his only son, not because it is in any way a good idea, but because God tells him to do it. Abraham proves willing to do so, and God rewards and praises him for his faith. Whoever wrote the Old Testament was certainly a Fundamentalist in some sense. If God says do it, just shut up and do it, even if it seems lunatic or even immoral. [In one of Woody Allen's collections of Short Stories, Without Feathers, there is a story called "The Scrolls". One of the "bits" in the story involves the discovery a "version" of the Binding of Isaac, which describes a God who stops Abraham from sacrificing Isaac while saying the equivalent of "Abraham, are you nuts? Didn't you know I was kidding?" I like that God better than the One in the original.]
While I have a lot of problems with the "Just Do What I Say" approach, a big one is the whole question of timing. After all, if God spoke to me tomorrow (from a Burning Bush or whatever), and I believed it was God, I would almost certainly do it. (Killing my son as a sacrifice, nope. If God decides to strike me with lighting as a result, ok. My own religious and moral beliefs do not begin and end with the "word of God", even if it is the word of God. Does this mean I am willing to substitute my judgment for God's? Yep. I may be weird, not to mention arrogant, but how many of you would actually sacrifice your child in that scenario?)
God comes to Man and says "write down the rules". Man does so. However, Man's concepts, knowledge, even language, did not then allow Man to write down things which, even among Fundamentalists, are now taken as true (i.e., the Earth is round; Heaven and Angels do not live in the sky immediately above the Earth.) Surely God must have known this. God must have also known that while Man not have been ready to abandon slavery when the books were written, Man would eventually figure it out. In short, God knew that change would occur. So, would not an Intelligent God allow for the equivalent of Constitutional Amendments - of some method of changing (not just explaining, changing) the lessons or directions of the Holy Book?
An aside - the Roman Catholics may have done a better job of allowing for new knowledge than other sorts of Fundamentalists. They have created a real live person who, if He needs to, can claim to be speaking in the name of God, and can, at least in theory, change the Rules (although I do not think the Catholic Church would put it quite that way).
Still, the problem is that once you write something down and declare it to be the Word of God, it is, like the Ten Commandments, carved in stone, which is not the only way how knowledge is (or at least should be) acquired by human beings. The classic way to really change a Religion is to simply start a new Religion, or at least a new branch or Sect, Christianity being the most obvious example. Some of these new groups will grow and prosper; some won't. [Question: The Mormons - The Church of Jesus Christ of the Latter Day Saints - are they "Christians"? I think so, but I know some Christians who disagree. Heck, I know Christians who claim that Roman Catholics are not really "Christians". I do not intend to criticize anyone by this observation/question. Certainly, I, and I think almost all of those I consider Jewish, believe that "Jews for Jesus" are not Jewish. I will come back to this "define the group" question in Point 3, below]
Still, my basic point is that Fundamentalism does not allow for changing of beliefs based on new evidence. That just not how "knowledge" really works.
Problem No. 2 - "cherry-picking"
Several things these Holy Books have in common; they are not short; they are often vague or obscure; some parts of them can be read as being contradictory to others. All of these things allow for their adherents (including but not limited to Fundamentalists) to pick and choose the parts that they want to emphasize (often called "cherry-picking"). Easiest example - the New Testament says a lot about, love, charity, feeding the poor, and loving the sinner but not the sin. However, many Fundamentalist preachers seem to focus a lot on the Old Testament [the wonderful comedian Lewis Black does a great routine on this. "That's Our Book; it wasn't good enough for them"], and emphasize the "smiting" (by us) of those who don't agree with us. My own branch of Judaism (Reform) quite openly chrry picks, and dismisses a number of traditional practices (which clearly appear to be required by the Torah) as mere customs- note, it's called "Reform" rather than "Reformed" because we acknowledge the need to keep increasing our understanding of just what God wants us to do). But even those Orthodox Jews I know cannot really explain to my satisfaction why some Mitzvot just are not followed any more.
The most blatant thing is that all of these Holy Books extol the virtues of Peace while suggesting that its readers kill at least some of their enemies because they are unbelievers or from a different tribe.
Which leads to Problem No. 3 - If it's the ultimate authority, a Religious text can be used to justify almost anything-and it will be
In a previous Post, I used the following quote from the late Senator Barry Goldwater:
"On religious issues there can be little or no compromise. There is no position on which people are so immovable as their religious beliefs. There is no more powerful ally one can claim in a debate than Jesus Christ, or God, or Allah, or whatever one calls this supreme being. But like any powerful weapon, the use of God's name on one's behalf should be used sparingly.
History and current events are rife with examples of justifying war, atrocity, genocide, torture, and almost anything bad in the name of religion. You can come up with your own. However, I would take issue with those who believe that any particular religion is "warlike" (Some may be more so than others and "younger" religions may be more aggressive, generally). Rather, I think (and I think Goldwater's quote suggests) the problem is more related to Fundamentalism, whatever its variety. If people believe that God really suggests that we worship or otherwise act in a certain way, and that God's word should be our prime directive, there's not much room for debate or compromise. After all, if God says "do it", we're supposed to just do it.
Please note that I do not exempt my fellow Jews from this tendency. We may tend to be less obnoxious (for lack of a better word) because of the "Chosen People" thing. The Torah and Talmud do not say that everyone should be Jewish or observe Jewish laws. Quite the contrary - the Torah and the Talmud are directed at Jews, and they tell us how we, not everyone else, are supposed to behave. Nevertheless, like all other Fundamentalists, when they have the power to do so, Jewish Fundamentalists have been known to attempt to force other Jews to behave "appropriately", even to the extent of asking Christian authorities to intervene to squash our own "heretics".
Here is where I get back to my "Mormon" question from point one. Fundamentalists, at least historically, have been particularly vicious to those of their own religion whom they believe have strayed from the true path. In short, heretics are often treated worse than non-believers. This may be largely due to both proximity and to the perception that one needs to struggle for the "soul" of one's religion. In any event, it reinforces one of my points - that Fundamentalists tend to be intolerant - and sometimes intolerance makes people dangerous.
I believe Religion, including "organized" Religion as well as a more general "spirituality", is, at least today, more of a force for Good than Evil, although I have my doubts sometimes. Moreover, Religion and/or God are not necessarily inconsistent with what I believe to be how the world actually works. Although I have friends whom I respect and admire who would consider themselves Fundamentalists, I cannot say the same for Fundamentalism, on either count. Enough.