Would Vouchers Endanger Science and Liberal Order?!

During Tuesday's “Caserollout” at LG's, I got into a fairly vehement argument with those assembled about state neutrality and the teaching of evolution in public schools. Although I was frighteningly outnumbered, I still believe I was right.
The deeper question, lurking beneath our debate, I think is this: Is it possible to maintain a distinctively modern liberal society without resorting to some kind of coercion to ensure that children come have a commitment to certain epistemic norms, and to certain beliefs thought to be required by those norms?
Our particular debate centered on whether liberal society in general, and a high-functioning scientific community in particular could survive a system where children were not formally taught to believe in the theory of evolution by natural selection.
My position is that neither liberal society nor thriving scientific practice require that the theory of natural selection be part of the curriculum.
Before I defend my position, let me say that I believe intensely that children ought to be taught scientific method and evolution in school. I think it is a parent's moral duty to ensure that their kids are so taught. However, I do not believe that they have a political duty to do so.
Similarly, I believe that parents have a moral duty to provide their children the most nutritious diet available, given their budget. However, I do not believe parents have a political duty to do so. Parents who allow their children too many calories, too much sugar, too much fat, too few vegetables, etc. (i.e., most parents, proabably), are failing to meet their moral obligations to their children. However, as long as parents ensure that their children are not clinically malnourished, they have met their political obligation to their children, as odious as their neglect might be.
Now, I think that we ought to ostracize and pressure parents who feed and educate their children badly. And I think it a quite good thing for folks to give a piece of their mind to parents and schools who fail to teach their children good science. And if ever you get a chance to convey truth to the children of the benighted, by all means, do it!
Now, here are some things to bear in mind…
First, in our current system, where public schools basically amount to a monopoly in education, and evolution is taught more or less everywhere, it turns out that 45% of people believe in creationism anyway. Behold the abstract from this Gallup poll:

Only about a third of Americans believe that Charles Darwin's theory of evolution is a scientific theory that has been well supported by the evidence, while just as many say that it is just one of many theories and has not been supported by the evidence. The rest say they don't know enough to say. Forty-five percent of Americans also believe that God created human beings pretty much in their present form about 10,000 years ago. A third of Americans are biblical literalists who believe that the Bible is the actual word of God and is to be taken literally, word for word.

Now, the USA, circa 2004, is one of the oldest, most stable, and most overall successful liberal societies in the history of the world. The USA circa 2004 may well be the most technological advanced and most scientifically progressive society in the history of the world. YET . . . a third of the population thinks the Bible is literal truth, and those who wrongly believe that evolution is false outnumber those who believe that evolution is true by millions. What's going on?
I think this shows us that (1) people compartmentalize, so belief in creationism has very little to do with one's performance as a computer scientist, mathematical physicist, accountant, or airplane pilot; and at least either (2) the public schools are just really lousy, in which case it's not really brilliant to argue that the indoctrinating power of the public schools is an essential bulwark between liberty and theocratic fascism; or (3) people's beliefs are influenced so heavily by their family and religious life that when there is a conflict between religious dogma and formal “book larnin',” religious dogma wins.
I accept (1), (2) & (3). Actually, I think the amazing number of creationists in America is a direct consequence of the utter travesty that is American public education together with the robustness of American religious institutions. The schools FAIL to teach kids to think, which makes them more susceptible to religious indoctrination.
My bold hypothesis is this: a competitive market in education would REDUCE the number of believers in creationism even if a much larger proportion of the population was educated in religious schools and specifically TAUGHT creationism. Why? Because there is every reason to believe that the overall quality of education would rapidly improve. The very best schools would innovate, and these innovations would be copied widely, as they are in every kind of market. Schools that failed to replicate the best techniques would quickly become substandard and graduates from these schools would have difficulty being admitted to institutions of higher learning and securing good jobs. So, even students who are being taught creationism are, at the same time, acquiring basic cognitive competencies both faster and to a higher degree of perfection than they are under our system of public school monopoly.
At the same time, it remains that we live in a mass media information society in which it is almost impossible to remain entirely isolated from conflicting points of view. (I became an athiest because of a book I read while working for my church!) Religious students who are overall better educated will, unlike many or most students today, have the intellectual capital necessary to really think through the merits of views that are in competition with the dogma they are fed in school. And this, I submit, would lead to a decrease in belief in creationism. I suspect that our current system, where most children receive an inadequate education, and where there is very little competitive pressure on the religious private schools that do exist, is a fairly ideal setting for the survival and perpetuation of religious myth and culture.
I have a number of other related issues that I'd like to take up later. Sorry for the free-associative nature of this post. For now, let me say that I don't think there is much to support the idea that a widespread voucher system, or a fully private system, would be any kind of threat to science or liberal society. Indeed, I think people who worry about other people believing in creationism would do themselves a favor by supporting a less coercive and more dynamic system of education.