Michelle Goldberg has a terrific piece exploring the intellectual roots of Michelle Bachmann:

Bachmann honed her view of the world after college, when she enrolled at Coburn Law School at Oral Roberts University, an "interdenominational, Bible-based, and Holy Spirit-led" school in Oklahoma. "My goal there was to learn the law both from a professional but also from a biblical worldview," she said in an April speech.
At Coburn, Bachmann studied with John Eidsmoe, who she recently described as "one of the professors who had a great influence on me." Bachmann served as his research assistant on the 1987 bookChristianity and the Constitution, which argued that the United States was founded as a Christian theocracy, and that it should become one again. "The church and the state have separate spheres of authority, but both derive authority from God," Eidsmoe wrote. "In that sense America, like [Old Testament] Israel, is a theocracy." ...
In the statehouse, Bachmann made opposition to same-sex marriage her signature issue. Both she and her husband, by all accounts her most trusted political adviser, believe that homosexuality can be cured. Speaking to a Christian radio station about gay teenagers last year, Marcus, who treats gay people in his counseling practice, said, "Barbarians need to be educated. They need to be disciplined, and just because someone feels this or thinks this, doesn't mean that we're supposed to go down that road."
In 2004, Bachmann gave a speech warning that same-sex marriage would lead to schoolchildren being indoctrinated into homosexuality. She wanted everyone to know, though, that she doesn't hate gay people. "Any of you who have members of your family in the lifestyle, we have a member of our family that is," she said. "This is not funny. It's a very sad life. It's part of Satan, I think, to say that this is gay."

The religious right has its origins and deepest roots in social issues, as Goldberg shows. But it has evolved into a more full-fledged worldview with coherent positions on economics and foreign policy that often motivate its believers just as strongly. That is a key development that the many analysts who have been dismissing Bachmann have failed to grasp. Twenty years ago, a figure like Bachmann would represent a sizeable but still minority constituency in the party, speaking to a cadre motivated by social issues but unable to represent the concerns of most Republican voters. (For instance, Pat Robertson, the televangelist who turned in a strong showing in the 1988 Iowa caucus but fizzled afterward.)

But Bachmann is a cutting edge religious right conservative, espousing an apocalyptic free market fundamentalism that's become virtually indistinguishable from the apocalyptic Randian worldview of the party's libertarian wing. Bachmann spent months addressing Tea Party rallies where she focused primarily on economics.  Meanwhile, the movement's embrace of right-wing Israeli nationalism has merged with mainstream Republican foreign policy thought. (Not just Bachmann but figures like Mitt Romney* and Newt Gingrich will appear at Glenn Beck's nut-fest in Jerusalem this August.)

The skepticism about Bachmann's prospects reflects an antiquated assumption that there's a natural ceiling within the GOP on the support base of a hard-core religious conservative. Yet both the movement and the party have changed in ways that make that less and less true.

*Update: Romney's campaign now says he will not attend.