Because I wrote a book with "Atheist" in the subtitle and I go on political TV shows to hawk that book, well-groomed meat puppets ask me why politicians like Michele Bachmann and Rick Perry are saying bugnutty Christian stuff.

I have an idea why these politicians have gone all religious. I think the problem comes down to the word "Christian" and what it has come to mean.

People didn't start self-labeling or getting labeled Christian until the last part of the 20th century. Before that, you might identify as a Baptist or a Southern Baptist or a Methodist. But there wasn't one identifier that put you in a fold with all the other believers.

There was no "Christian nation" for the simple reason that the Christians were afraid of one another. America was founded on Christians not trusting each other.

Robert Ingersoll, "The Great Agnostic" of the 19th century, was courted by many politicians. Candidates wanted Ingersoll on board to show they were open to free thought. After all, if they were open to Ingersoll, a nonbeliever, surely they'd tolerate the other Christian groups too.

I'm no Ingersoll, but I'm an atheist who, like him, speaks publicly about not believing, and I can assure you today's politicians don't court me.

When I was a kid, politicians wanted to avoid talking about religion if they could. John F. Kennedy couldn't duck the issue, being Catholic and all. So he reminded Americans that religion shouldn't be an issue, that he was concentrating on big things like poverty and hunger and leading the space race. When he finally got around to talking about religion, he said: "I believe in an America where the separation of church and state is absolute." Can you imagine a presidential candidate talking that way today?

Jimmy Carter happily identified as born-again, and that phrase and the magic word Christian started to be used more and more. One American president who mentioned religion constantly was Bill Clinton. He did not care what church he appeared in as long as he was seen at a church.

And, now, we come to Bachmann and Perry.

I've used pornographic images, obscenity and poetry to try to make even the most doubtful blush, but I've never come close to Bachmann's insult to the honest faithful when she said the suffering and casualties of natural disasters were her God's message to wayward politicians. What she said was disgusting and not generally Christian at all. But her blasphemous message was delivered on the news as just that.

Bachmann was a longtime member of the Salem Lutheran Church, a small denomination that has some odd teachings. But even in the broadest definition of Lutherans, there are only about 13.5 million. Now Bachmann has moved to Eagle Brook, an evangelical church. Even if she wins all the evangelical vote, that gives her only 26.3 percent of the American people. With those percentages, you need to shut up about religion.

Perry has moved away from his Methodist background (which claims about 8 million American members) and moved to the Lake Hills Baptist Church, which went on to drop the word Baptist to be more inclusive. When Perry did his big apolitical political rally in August, he was careful to call it nondenominational. It was Christian. Now let's watch Mitt Romney, a Mormon, as he works on trying to convince Americans that his sect, with its belief that the Garden of Eden was in North America, is just another Christian offshoot.

Atheists are growing fast, from under 2 percent to about 8 percent just in this century. If you throw in self-labeled agnostics and those who identify as not religious, you're getting up to around 20 percent. Evangelicals are about 26 percent, Catholics about 23 percent, Jews, 1.7 percent, Mormons also 1.7 percent.

Let's just hope our politicians keep expanding the group of people they want to serve. Rather than embracing Christian as the magic word of politics, we can move on to the truly magical word: American. And maybe we can even go a step further and make the magic word "humanity."

Jillette, half of the magic comedy team of Penn & Teller, is the author of "God, No!" He wrote this for the Los Angeles Times.