The propagandists of the religious right shout it aloud as their battle cry: "America is a Christian nation!" And in the trivial sense that ours is a nation populated mostly by Christians, this is true. But in the sense they mean it, that Christianity was intended to occupy a privileged place in the law — or worse, that Christianity was intended to be the only belief professed by Americans — it couldn't be more false. Although religion in general, and Christianity in particular, play a dominant role in our public life, ours is a secular nation by law. And befitting that heritage, America has always played host to a lively tradition of freethought, unorthodoxy and religious dissent, one that dates back to our founding generation.

To name just one example, Thomas Jefferson rejected miracles and special revelation — he famously created his own version of the New Testament, which kept only the moral teachings and parables and cut out all the miracle stories — and encouraged his contemporaries to "question with boldness even the existence of a God." He himself was a deist, not an atheist, but this subtle distinction was lost on his contemporaries, who hurled accusations at him every bit as vicious as today's TV attack ads. For instance, in the presidential campaign of 1800, the Gazette of the United States editorialized as follows:

At the present solemn moment the only question to be asked by every American, laying his hand on his heart, is 'shall I continue in allegiance to GOD—AND A RELIGIOUS PRESIDENT; or impiously declare for JEFFERSON—AND NO GOD!!!'

Jefferson's political opponents denounced him as a "howling atheist" and a "French infidel," and paranoid rumors circulated that, if he became president, he would order all Bibles to be confiscated. Of course, in the end Jefferson was elected to two successful presidential terms, and the feared wave of atheistic persecution failed to materialize.

But stories like these aren't just historical footnotes. Just as freethinkers have always had their place in our nation, the strategy of slandering and demonizing them for political gain is likewise alive and well, as I found out for myself in 2008.

In that year's North Carolina Senate race, Elizabeth Dole, the Republican incumbent, was running against Democratic challenger Kay Hagan. In the waning weeks of the campaign, Hagan attended a fundraiser at the home of Woody Kaplan and Wendy Kaminer, advisors to American Atheists' Godless Americans Political Action Committee. The Dole campaign found out about this and tried to make political hay out of it, releasing a campaign ad which said:

"A leader of the Godless Americans PAC recently held a secret fundraiser in Kay Hagan's honor… Godless Americans and Kay Hagan. She hid from cameras. Took Godless money. What did Hagan promise in return?"

When I saw this ad, I was incensed. (Can you imagine a political ad which attacked a candidate by saying, "He attended a secret fundraiser held by the Jews and took Jewish money. What did he promise in return?") I dashed off a blog post titled "Why I'm Donating to Kay Hagan," expressing my anger at politicians who try to drum up anti-atheist bigotry to win votes, and wrote a check to the Hagan campaign. I thought nothing more of it until a few weeks later, when I found out that my post was being featured in another anti-atheist ad by the Dole campaign.

The ad highlights my statement that "Hagan ought to be rewarded for inviting nonbelievers onto her platform," as if this were a bad thing. It portrays atheists not as fellow citizens entitled to take part in the democratic process, but as agents of a sinister and un-American conspiracy — the same ugly slander that's historically been used against immigrants, Roman Catholics, Jewish people, gays and lesbians, and every other minority that seeks out politicians who will defend their interests.

Clearly, Dole was counting on a wave of outraged, prejudiced voters to flood the polls and propel her to victory. But her campaign's open appeal to anti-atheist bigotry may have produced a bigger backlash than she had expected. According to the Charlotte Observer, the Hagan campaign received 3,600 contributions within 48 hours of Dole's "Godless" ad, many of them presumably from nonbelievers upset at being dragged through the mud by right-wingers trying to score political points.

Unfortunately, Hagan herself turned out to be no friend of atheists. Although she was happy to accept our donations, when her association with us became an issue, she fled to the safe ground of piety-drenched politics. Her campaign released an ad accusing Dole of "attacking my Christian faith," going so far as to threaten a defamation lawsuit. It would have been nice to see some defense of the idea that America is a secular nation where a person's faith has no bearing on their fitness for public office. Instead, her response consisted solely of, "Yes, I believe in God and how dare you imply otherwise!" Effective, perhaps, but cold comfort to atheists who had for some reason assumed that we have as much right to be involved in politics as anyone else.

But despite this disappointment, there was a heartening outcome. For whatever reason — whether it was the flood of donations from outraged atheists, or Hagan's strong protestations of piety, or because the "Godless" ad simply failed to change enough voters' minds — on Election Day, Elizabeth Dole was defeated by a solid margin, and Kay Hagan became the new Democratic Senator from North Carolina.

As the Hagan episode shows, even many Democratic politicians, who should rightfully be our allies, feel that outspoken atheism is a disqualifier for public office. John Kerry gave voice to this sentiment in November 2007:

The vast majority of Americans say they believe in God… The vast majority of America, at some time, goes to church, and I think it matters to people. When you are choosing the president of the United States, people vote on the things that matter to them.

So I think it is probably unlikely that you are going to find somebody who stands up and says, 'Well, I don't believe in anything,' and you'll get a whole bunch people who get excited about voting for that person… It's just a fact.

Even Barack Obama, despite having been raised by a nonreligious mother, has been no friend to atheists — something we found out on the first day of his presidency, when he invited the anti-choice, anti-gay-rights, anti-stem-cell-research right-wing pastor Rick Warren to speak at his inauguration. Breaking a clear campaign promise, he's also continued the George W. Bush "faith-based initiative," which hands out government money to religious groups which openly proselytize, discriminate in hiring, and face no outside accountability. And polls continue to show that atheists are among the most reviled and least trusted minorities in the U.S., even more so than Muslims or gays.

Some corporations have been accused of having a "glass ceiling," an invisible barrier that prevents women and minorities from rising to the topmost positions. In that sense, American politics clearly has a "stained-glass ceiling," a de facto barrier to atheists running for office. Despite the many great Americans who've been nonbelievers, despite the guarantees of secularism written into our Constitution, outspoken atheism is still seen as an insurmountable liability for anyone who seeks to serve our country as an elected officer of the government.

Why is this? It's not because atheists are so rare that politicians can safely ignore us. On the contrary, nonbelief is far more common than many people realize.

The definitive word on atheist demographics in the U.S. is the 2008 American Religious Identification Survey (ARIS), a massive study that questioned over 50,000 Americans about their religious beliefs. The ARIS found that self-identified atheists and agnostics account for 1.6 percent of the population of America, or about 3.5 million people. But the ARIS also asked people in-depth questions about what they really believe. And based on their results, the survey's authors concluded that whether they choose that word to describe themselves or not, 12 percent of Americans are atheists — over 36 million of us!

To put that number in perspective, there are about as many atheists in America as there are members of all the mainline Protestant churches — Methodist, Lutheran, Presbyterian, Episcopalian, and United Church of Christ — combined. There are ten times as many atheists as there are Jews or Mormons. The only two religious groups in America that outnumber atheists are Baptists and Roman Catholics. But both of those groups have seen their membership as a percentage of the population decline steadily since 1990, while the non-religious have grown proportionally in the country as a whole and in every state. And the numbers show a clear trend: Every generation since World War II has exhibited higher rates of nonbelief, now up to 20 percent among those born since 1977.

So, atheists don't lack the numbers. Nor do we lack passion or political interest. In fact, the opposite is true: Atheists have one of the highest rates of political participation of any group. A 2008 study by the Pew Research Center found that 82 percent of the non-religious are very or somewhat likely to vote, an astonishingly high turnout level. In fact, the only group more likely to vote is Christian evangelicals. But the political loyalties of evangelicals are settled already, while non-religious voters — again according to Pew — are disproportionately likely to be independent voters whose choices often determine the outcome of an election.

Given these facts, politicians should be lining up to court us. On a purely numerical level, atheists are a large, potentially influential group. We're highly motivated to get out and vote, more so than almost any religious group. We tend to be swing voters, the kind that makes all the difference in close races. And most of all, atheists are common among the young, and good politicians know that political loyalties established at a young age usually last for a lifetime.

So why aren't candidates seeking atheists out and appealing to us for our support? Why is the political class, even the liberal political class, so fearful of being associated with us?

The obvious answer is that the pervasiveness of anti-atheist bigotry makes it political suicide to associate with us. (Elizabeth Dole failed in her attempt to appeal to it, but that doesn't mean it doesn't exist.) But I think there's a deeper answer that explains both why that bigotry exists in the first place and why politicians so habitually neglect us: Atheists don't lack the numbers or the passion. What we lack is the organization.

Organized religions have two built-in advantages: they have large followings that are accustomed to unquestioning loyalty, and hierarchical structures through which the leaders can issue marching orders to the flock. This means it's easy for them to orchestrate coordinated actions, like marches, protests and letter-writing campaigns, that are highly visible to politicians and journalists. Atheists, by comparison, are a fiercely independent and contentious bunch — and while I wouldn't change that if I could, it does make it harder for us to act in unison in the ways that make politicians take notice. It also makes it more difficult for us to mount a swift, strong and coordinated response to the slanderous stereotypes that are habitually heard from pulpits and in the media.

But if we can overcome that and become politically organized — and there's much evidence that this coalescence is already happening — the potential benefits are enormous. Atheists don't agree on everything, but I'm confident that we agree on enough to form a constituency that couldn't be lightly dismissed. The rise of atheists as a political force, if it succeeds, wouldn't just benefit atheists, but would have positive effects on American society in general and possibly even the world as a whole.

After all, most of the goals we share are also goals of the broader progressive movement: greater protection of free speech, firm separation of church and state, increased funding for science education and research, equal rights for LGBT people, and greater public support for reason and rationality. The idea that we want to take away people's right to pray or worship in private, or even to preach their beliefs in public, is just as much of a lie today as it was in Thomas Jefferson's time — but we do unapologetically demand that government employees, when acting in their official capacity, take no action to endorse or aid any specific religion or religion in general. This is no more than the Constitution already requires.

The global arena, also, would benefit from greater atheist involvement. If you list the evils that afflict humanity on an international scale — transnational religious terrorism; the abuse and subjugation of women; the denial of human rights in dictatorships and theocracies — you'll notice that many of them have this in common: they're all rooted in primitive, violent, patriarchal religious worldviews, and derive their strength from the excessive power and privilege accorded to faith. Again, a stronger atheist presence on the international stage would be as welcome as a cool breeze in the hothouse of fundamentalist religion, which has so often been used to justify ongoing oppression and inequality.

Imagine the kind of world we could live in if atheists were a political force. It would be a world where secularism is the unquestioned law of the land, where religious groups wouldn't interfere in politics unless they could put forward arguments backed by evidence that anyone could examine, and not just appeals to faith. We'd rely on science and rationality to shape public policy; humanity would heed the voice of reason, rather than gut feelings or superstitious taboos. In this world, the religious arguments propping up tribalism, racism, and the oppression of women would wither away; the decrees of unelected and unaccountable authorities would fade into dust, and democracy and the liberty of the individual would be the guiding principles.

Religion isn't solely responsible for all the world's evils, but — particularly where it goes unchallenged and unaccountable — it plays a role in a surprisingly large number of them. Even if it doesn't fade away entirely, which I don't expect to happen anytime soon, it's likely that the pressure of atheistic critiques would force it to become more moderate, more enlightened, and more humane. A world where atheists held political sway wouldn't be a utopia by any means, but I'm confident in asserting that it would be more peaceful, fair and free than the world as it is now — and this makes it a goal well worth fighting for.