The media spotlight has focused on the growing split in the Republican Party between its corporate-business wing and the libertarian-leaning Tea Partiers. But what about the third leg of the GOP tripod, the one that used to get all the attention: the evangelical Christian religious right? That’s where the spotlight ought to be.

We know the corporate-business types want an active federal government, because it can be counted on to serve their interests, especially if Republicans regain control of it. We know that the libertarians, who are the driving force in the Tea Party, want to shrink government; that’s their whole reason for being.

What we don’t know yet, and what will determine the fate of the GOP, is which way the religious right will break in this intramural fight over the role of government. Even the conservative evangelicals themselves don’t know, because the split in the GOP runs smack down the middle of the religious right.

Many politically active evangelicals are happy to be Tea Partiers and align with the libertarian call for smaller government. They see government as a force imposing its secular ways upon them. And Tea Party politicians have been equally happy to talk the religious right talk because it wins them votes.

Many other evangelicals will join the corporate-business Republicans in rejecting the Tea Party’s extremist anti-government agenda. They’ll see why Tea Partying is a trap for them. Only a powerufl government can do the things evangelicals want most, like banning abortion and gay marriage, and more generally, imposing strict rules of personal behavior on every American. The more the Tea Party weakens the government, the more it deprives the religious right of its most potent tool. That should be easy enough for most conservative evangelicals to see.

What most won’t see, though, is the hidden place where evangelicals and libertarians do meet: way back in U.S. history, where both movements were inspired by a radical worldview. Just as the libertarian call for less government has its roots in radical, not conservative, assumptions about human nature, so the religious right’s call for government intervention has deep roots in evangelical demands for policies that were radically progressive at the time. Some of them are still radical, even by today's standards.

As early as the 1820s, the evangelical style of Christianity was beginning to dominate American political life. It didn’t stop dominating until the 19th century was over.

Looking back across the history of that century you’ll find evangelicals, demanding strong government intervention in everyone's life, popping up in all sorts of places. And most of those places are well to the left of where you might expect them, if your view of evangelical politics is shaped only by the era of Ronald Reagan and Jerry Falwell.

Most famously, evangelical Christians led and filled the ranks of the movement to abolish slavery. Some (though far too few) even took the lead in treating African Americans as genuine equals. The best recent writing on the causes of the Civil War shows that evangelicalism was a crucial factor creating widespread popular resistance to the “peculiar institution.”

Without the spur of evangelical fervor there probably would have been no Republican Party, no President Lincoln, and no secession of the South. Slavery would not only have continued in the United States; it probably would have spread throughout the territories that became the new states of the Southwest, making it that much harder ever to abolish.

Antebellum evangelical reformers also took the lead in demanding that government provide free public education for all, more humane treatment of prisoners and the disabled, and more equality for women. Of course, most of their specific policy prescriptions seem too conservative by today’s progressive standards. But in their own day they were out on the cutting left edge of political life. And one of their demands—that government renounce war as an instrument of national policy—still sounds as radical as ever.

You’ll find all of these examples, and more, if you pick up any good book on 19th-century U.S. history.

I picked up one such book at random, just as I was beginning to write this column: Alan Trachtenberg’s The Incorporation of America, one of the most insightful histories of the Gilded Age, from the 1870s to the 1890s. When historians go looking for evangelicals supporting left-leaning government policies, they almost always look at the era of reform before the Civil War, not the Gilded Age that followed it. Yet just thumbing through Trachtenberg’s book I easily found evidence that the pattern lasted right through the 19th century.

Trachtenberg points out the powerful evangelical impulse in two of the era's greatest political bestsellers, Henry George's Progress and Poverty and Edward Bellamy’s Looking Backward. George wrote glowingly of "the noble dreams of socialism." Bellamy advocated "the religion of solidarity… a system of public ownership… to realize the idea of the nation … as a family, a vital union, a common life."

Both denounced the injustices of the emerging corporate system with "evangelical fervor," says Trachtenberg, sustained by "religious emotions of 'solidarity.'"

But there was more going on than just utopian words. There were workers organizing in the factories and the streets, dominated in the 1870s and 1880s by the Knights of Labor. The Knights intended to use government to achieve their goals—goals that today's progressives still struggle for, like a fair and just income tax structure, guaranteed equal pay for women, and government ownership of utilities and transportation systems.

And they built their movement upon "an unmistakable fusion of republicanism and evangelical Protestantism," in Trachtenberg's words. "Workers found in Protestantism a profound 'notion of right' for their struggles." They made “'the religion of solidarity’ proclaimed by Edward Bellamy and other Protestant reformers … a living experience within labor.” Obviously they saw no conflict between evangelical Christianity and a strong central government enforcing laws to create economic justice.

By the 1890s the Knights’ leading role in labor movement had been eclipsed by the American Federation of Labor. But as the Knights declined, the spirit that moved them was being picked up by an eclectic mix of movements that came to be grouped under the umbrella term, Populists. Their program was laid out most famously in the 1892 declaration of the People's Party, which demanded that government support the interest of "the people," not "capitalists, corporations, banks, trusts."

That declaration was "composed in evangelical accents" and "rang with echoes of revivalism" as well as "backwoods democracy and grassroots outrage," as Trachtenberg writes. "Populist spokesmen clothed themselves in the garb of righteous evangels."

Like the Knights, the Populists were on a crusade to eliminate sin. But their political ideas also "drew from the movement's roots in native radicalism, in a secular rhetoric of 'equal rights' and 'anti-monopoly.'" And the main weapon Populists aimed to use was political power—enough power to make sure that their policies were enacted through government legislation, regulation, and strict enforcement.

Like most historians, Trachtenberg traces the decline of the Populists to their fateful decision, in1896, to join with the Democrats in making William Jennings Bryan their joint candidate for president. Bryan ran three times for the top job and lost all three times. Today, on the left, he’s most remembered as the evangelical Christian zealot who decried the teaching of evolution in the 1924 Scopes trial. But the infamous trial came near the end of his long life.

For most of that life he, more than any other American, carried the banner of radical reform in the name of God. It's worth reading the details in Michael Kazin's recent biography of Bryan. Kazin, a leading authority on Populism and an important progressive intellectual in his own right, makes it clear that in the late 19th century, and on into the early 20th, millions of evangelical Protestants saw it as a religious duty to demand that a strong government right the economic wrongs of the corporate capitalist system. The left in that era could not have emerged as a significant force without the tremendous boost it got from evangelical faith.

All this history should be more than mere curiosity to us. The Knights of Labor, the Populists, and the Bryanites were in many ways the forerunner of today's progressive left. Their fusion of evangelical Christianity and strong progressive government holds lessons for, and poses questions to, progressives today.

The Republican Party may or may not be cracking up. Cracks in the GOP alliance don’t necessarily mean any advantage for progressives, of course. But they are windows of opportunity, if the left knows how to take advantage of them. It’s all a question of strategy.

A smart first step for progressives is to do whatever we can to widen those cracks. It’s the religious right, long the progressive left’s favorite target, that is now the richest target of opportunity. Because politically progressive evangelical Christianity is not merely a relic of the 19th century. It’s making a comeback.

That presents left progressives with a challenge. In your struggle for justice, would you ally with people who share your commitment to greater economic equality but would like to see government ban abortion and gay marriage? Today the question may seem abstract and hypothetical. Soon enough it may become a very real issue of debate for progressive strategists, and there are bound to be good arguments on both sides.

However, everyone should be able to agree that at least progressives outside the evangelical community should begin talking to folks inside that circle who are open to hearing the progressive message. Evangelicals will have to filter the message through their own beliefs, which means phrasing it in a somewhat different language.

Smart progressives will start learning that language, figuring out how to communicate with evangelicals and discover common ground. Smart progressives will also learn how to remind evangelicals, gently but persuasively, of their own radical political history, which many may not know.

The main goal here should be to make the progressive tent wide enough to make room for evangelicals. Though we are far from the 19th century, evangelicals can now, as then, bring a unique kind of energy into progressive movements that can pay off. As a side benefit, moving evangelicals to the left will also widen the cracks in the shaky conservative alliance and hasten the day when it can no longer hold itself together.