The great weight of science indicates that the first part of that argument is basically correct (i.e., one's sexual orientation is determined by biology), but the latter part is somewhat misleading and merits scrutiny. After all, though we can choose our religious affiliation, none of us can ultimately choose what we truly believe or don't believe. I disbelieve in unicorns and I could not choose otherwise, just as I also could not believe, absent new evidence that changes my understanding of geography, that New York is south of Florida.

The difference between personal secularity and sexual orientation is not that one is a choice and the other isn't, because both have causal factors that eliminate choice. The difference is that sexual orientation is determined almost entirely by biology, whereas religious disbelief is much more a combination of biology and environment. But in both cases, there's really no choice.

If Richard Dawkins, perhaps the world's best-known atheist, had been born in the thirteenth century, chances are he would have been theistic, believing in one kind of god or another. But having been born in the twentieth century, having experienced his life as he has, can it really be said that Dawkins chooses to be an atheist? His status as a nonbeliever is a result of his biological composition (particularly his brain function) combined with the knowledge he has gained through his life experiences. It really is not a choice at all.

If more individuals today are religious skeptics than in centuries past, that is mainly because accumulated knowledge has inclined more people toward such doubt. As Dawkins himself has said, it would have been harder to be an atheist hundreds of years ago, when so many mysteries about the universe had not been answered. Though skepticism has always existed (the history of religious skepticism is covered wonderfully in Jennifer Michael Hecht's Doubt: A History), the scientific discoveries of the last few hundred years have filled in so many gaps that the idea of a Grand Designer with some kind of special affection for humans seems more implausible than ever to many.

But this does not mean that today's religious skeptics choose not to believe. Instead, we can see that personal secularity is primarily the result of brain function combined with access to knowledge, information, and a social setting allowing disbelief. Given the right conditions, the result will be an individual who does not accept explanations.

Interestingly, we can see that in many ways believers don't really choose either, but when we consider theistic beliefs we see different causal environmental factors at work. Early indoctrination by family, for example, is a key environmental factor that promotes such beliefs in many, as is the pro-religion conditioning that one receives from the community and broader society. Even if the overt promotion of by society is mild (which usually isn't the case in much of America), prevailing social views that disapprove of open disbelief will often discourage serious exploration of secularity.

Thus, although causation is always complex and the specifics are going to vary from one individual to the next, in general we find two interesting patterns with regard to the formation of religious belief and disbelief. That is, the major environmental factor that promotes disbelief (and discourages belief) tends to be accumulated knowledge, whereas the most significant environmental factor in promoting belief (and discouraging disbelief) tends to be family and social indoctrination.

Understanding this, we better understand how and why the Religious Right acts as it does. It wants the environmental factors to be slanted in its favor as much as possible, and that means it must hinder access to the knowledge that encourages secularity (by obstructing evolution , for example), and it must maximize family and social pressures that encourage religiosity. This is why the Religious Right is so in advocating governmental religiosity, and why it also promotes the ridiculous idea that morals and values are synonymous with religion.

By creating a social and political environment where religion is presumed to be central to and patriotism, and where open personal secularity is seen as unacceptable, religious conservatives lower the likelihood that more will gravitate toward a secular lifestance. This is why they support laws, none of which were approved by the Founders, encouraging Americans to believe that they must trust in God (per the national motto), that the nation is under God (per the Pledge of Allegiance), and that we must have an annual National Day of Prayer. They want us to believe that America is a "Christian nation," because such a social and political environment strongly discourages personal secularity.

In such an atmosphere, where the overwhelming assumption is that God-belief is important, and where the general public lacks knowledge of science and doesn't truly value critical thinking, it wouldn't be accurate to say that most Americans choose belief. Rather, what is really happening is that itself tends to produce individuals who believe, while it simultaneously creates barriers to secularity.

To be sure, the secular movement tries to slant the environmental factors in its favor also, but those efforts don't involve the intellectual dishonesty that the Religious Right utilizes. Secular Americans try to increase access to accumulated knowledge, encourage critical thinking, and create a social environment that does not scorn secularity. This is hardly diabolical.

Thus, while sexual orientation is not a matter of choice, we should realize that neither are one's sincerely held beliefs about divinities. One can hide or misrepresent one's real beliefs, but one cannot change those beliefs on command. Still, we should also recognize that the biological aspects of secularity are not directly analogous to the biological nature of sexual orientation. Whereas a thirteenth-century Dawkins would most likely have been a theist, a thirteenth-century Elton John no doubt still would have been gay.

Finally, if environment is key to the spread of secularity, and if the explosion of knowledge in recent centuries has made the idea of disbelief more compelling, it would seem that the long-term trend toward secularity, even if slow, is likely to continue. In fact, it is remarkable that secularity has spread so impressively even though powerful forces have tried to shape the environment against it.

Nonbeliever Nation: The Rise of Secular Americans, David Niose's critically acclaimed survey of the culture wars, will be released in paperback on December 17, 2013.

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