Most religions have some form of sacred texts that they believe to have been divinely inspired and to constitute the basis of ultimate truth. Not being a religious person, I don't regard any documents as having such status. Most conservatives in the US do tend to subscribe to traditional Christianity and attempt to link the Bible as they wish to understand it to the constitution as they wish to understand it. The framers of the constitution are given the status of Moses receiving the stone tablets and it all becomes eternal and unchangeable.
The white men who met in Philadelphia for the constitutional convention were a varied collection of individuals. They were the politicians of their day. When you look at them as individuals, most of them were not possessed of particularly outstanding abilities. They were people who were operating in the context of a specific culture in a specific time and a specific place. What was unusual about the situation was that a new nation and its government were being established. What came out of the process was very much a political document comprised of political compromises that were at times quite arbitrary. The most arbitrary of these was the clause allowing slaves who were denied citizenship to be counted as 3/5 of a person for the purposes of apportioning congressional representation.
The constitution's framers did not lay claim to having discovered eternal truth. That is why they made provisions for the adoption of subsequent amendments to its content. That makes it very much a political document. Two areas that consistently inspire the most impassioned debate are rights of speech and expression and the regulation and control of fire arms. These are the first and second AMENDMENTS. They were not even part of the original constitution. Even the first 10 amendments known as the bill of rights were adopted concurrently with the constitution, it was decided that they were politically necessary to assure its ratification. They were essentially a political after thought.
The idea of making amendments difficult to pass is intended to promote political stability. However the initial ratification in 1789 there have been 17 more amendments to the constitution. The 18th amendment, prohibition of alcohol, was eventually deemed to be politically not viable and was repealed by the 21st amendment. That experience is pretty strong evidence that constitutional government is a process of trial and error.
The entire business of judicial review and constitutional interpretation was left hanging by the constitutional convention. It was not formally addressed in the document and the supreme court established a precedent for it in the case of Marbury v. Madison. Having the courts serve such a function has proven to be necessary and useful. However that too is very much a political process that is by no means fool proof. Anybody who things that SCOTUS is a source of divine truth should just read the chaotic decision in the case of Bush v. Gore. Controversial cases are often decided by a split vote of 5 to 4. While that is sufficient to establish a working legal precedent, it is hardly evidence of an over riding national consensus.
The US is in the process of a broad demographic sea change that is pointing toward a time in the not too distant future when the people of white European decent who have been running this country since its founding are going to be in a minority. This is not the first time that the nation has had to struggle with its demographic identity and we can find trails of those struggles in constitutional and legislative history in instances such as the 13th and 14th amendments and the various immigration and naturalization acts.
The election of Barack Obama as the first president who was not a white man has served as something of a touch stone for the tensions being generated by these changes. It is about much more than him as an individual, but he occupies a position of symbolic importance. The people who are feeling the most threatened by these changes are attempting to wrap themselves in the flag and the constitution. They want to portray the constitution as a sacred text that enshrines their traditional privileges of a racial patriarchy.
The issues of speech and guns are and will likely continue to be primary battle grounds for these debates. Look at the people who are typically demanding unlimited rights to free speech and unrestricted rights to own and carry any and all forms of fire arms. They are almost always white men who are trying to retain control with claims of their inviolable traditional rights. The ideas of American exceptionalism would have us believe that everything that the US has ever done is a model for the rest of the world and that any suggestion that we might learn something useful from the experience of other nations amounts to both treason and heresy. We can look to nations such as Canada and the UK and find different models for the regulation of speech that threatens to do harm to others and of fire arms that pose a danger to people who are minding their own business. Neither of those nations has ever been in much danger of turning into a fascist dictatorship.
We live in a complex and changing world. Our efforts to survive in such a world must be supported by flexible and responsive social and political institutions. What seemed to be a workable political compromise in 1789 doesn't necessarily hold up in the circumstances of 2013. We have found it necessary to modify our political institutions in the course of our history. We will continue the need to modify them in the future. There always have been and always will be people claiming that doing so will lead to the utter destruction of out god given heritage.