A diversion from science, for a moment.
I recently saw an exchange where an atheist made a claim: The Pledge of Allegiance is un-American.
Familiar claim, with familiar lines. It was changed in the 1950s, and because of anti-communist hysteria. It's offensive to atheists. It's an insult to America, which values the separation of Church and state. It's divisive.
And so on.
Now, nonsense innate to those claims aside, this is where many theists - I'm speaking broadly here, because this question is not one of Christianity, but of mere theism and deism in the broad sense - seem ready to capitulate. Yes, though they may believe atheism to be incorrect, atheists are by and large good and moral people. A belief in God is not essential to our secular country. We are founded on secular ideals, ones all men can agree to, and God or belief in God is simply not an issue.
Popular move, as I said. Years ago, I may have been tempted to make it myself. It sounds great, after all - no denying that, that appeal to equality in a very modern way. It sounds charitable and noble too, holding up certain ideals even to those one bitterly agrees with. It sounds nice, to say that a commitment to American ideals compels the devoutly religious to see atheists, at least on some level, as comrades who are committed to some core ideas. Common ground and all.
Here's the problem: It's a lie. America was founded by Christians and deists of a particularly Christian cultural, moral, and philosophical grounding. There is no way to remove God from the equation without divorcing oneself from the ideals the country both was founded on and relies on to make sense of its identity.
Stanley Fish's piece again becomes relevant in making this point, but I'll boil it down. America was founded on the idea of God-given rights, of mankind universally being endowed with a nature which not even kings (or, dare I say it, elected officials) were permitted, ultimately permitted, to violate. Remove God, assert a philosophical worldview such that there are no such things as innate and inviolable rights (and if God is denied, it becomes nigh impossible to avoid this), and you have abandoned the fundamental American commitments in every meaningful way. Remove God, and you make most of the acts and claims and visions of the founding fathers meaningless in the process.
Now, it can be objected that there are other ways to run a country (no doubt - The founders knew this firsthand), or that we should change those commitments. But that's to concede the point I'm making. A mormon, hindu, catholic, protestant, jew, muslim, deist and theists of wide variety are in principle able to meet these original and long-lasting commitments. The atheist, the person who denies God and with Him God-given rights, cannot. It is not enough to merely be in favor of those rights personally while thinking that ultimately they're just laws and rules society agrees upon (and then, only for now.)
I'm sure that (the fact that I'm a nobody aside) this will make someone furious. I'm past the point of caring, because this is a fact of history that nobody can change - though we can certainly ignore it or play make-believe. I just refuse to play that game anymore. The Founding Fathers had a view of rights, man, nature and nation which amounted to broad net. Again, in principle, very many men can be caught up in that net. But it doesn't catch everyone. It was never intended to.
Edit: I'll also point out it isn't as if every theist instantly qualifies either. A deist or theist can conceivably deny that man has certain inalienable rights, or has certain rights afforded to him by nature, and so on. And if so, well, they're in a similar boat. People seem to think being true to core American values (if they even accept such things exist) is absurdly easy. It's like getting into CostCo is more intellectually demanding.