Should John McCain eke out a victory on Tuesday, there can be no doubt that, amid the sounds of weeping and gnashing of teeth emanating from disappointed Democrats, there will also be bitter accusations of racism directed at American voters. Indeed, Slate columnist Jacob Weisberg has already published the indictment pre-emptively, in an Aug. 23 article subtly titled "If Obama Loses, Racism is the Only Reason McCain Might Beat Him." Nowhere will this charge be made more angrily than against the evangelical Protestant community.

The sweeping accusation of racism is outrageous, but there is surely some reason to believe that some whites, some evangelicals among them, are silent about their decision to vote against Barack Obama because they know that their motives cannot bear scrutiny. By the same token, of course, there are an incalculable number of whites, including evangelicals, who will be voting for Sen. Obama precisely because of the color of his skin, rather than the content of his character or his policies. They are motivated by a desire to demonstrate their goodwill (and perhaps expiate lingering feelings of guilt).

With the 1980 presidential elections, white evangelicals became one of the most reliable constituencies for the Republican Party, supporting it not only on social and cultural issues such as abortion but also on economic policy, tax cuts and military assertiveness. Evangelicalism was identified almost exclusively with its most visible leaders, men such as Jerry Falwell, Pat Robertson and James Dobson, all of whom were political conservatives as well as theological ones.

But there has long been a small but cohesive evangelical left that chafed under the weight of such identification, actively distanced itself from such leaders, and sought to emphasize economic equity, social justice, environmental stewardship and a more irenic foreign policy.

Today, evangelicalism seems to be increasingly divided. The evangelical left has seen its visibility and influence grow in recent years, as the threat of global warming and economic issues became more frequently featured in the pages of Christianity Today and other bellwether evangelical publications, and as the National Association of Evangelicals came under the control of a new generation of more liberal evangelical leaders. With the 2008 campaign, the evangelical left has been presented with a candidate it can support enthusiastically, despite his extreme views on abortion. For them, it almost seems that race has trumped the protection of life as a fundamental issue. Richard Cizik, vice president of the NAE, told Beliefnet that evangelicals whose prejudices keep them from voting for Sen. Obama "ought to be embarrassed, and held accountable in the church." One has the sense that he is more than ready to level such accusations at his co-religionists should the election produce unsatisfactory results.

Which of these factions in evangelicalism's divided house is more reflective of its essential character? In truth, both have a strong claim. Evangelicalism has always been centrally concerned with social reform as the necessary expression of spiritual regeneration. It is not merely a religion of inwardness. Nor is it a religion devoted to maintaining the status quo and propping up social elites. Instead, it challenges settled arrangements and champions the lowly and the marginalized. Evangelical transformative zeal was at the very heart of nearly all the most important reform movements of the 19th century, especially abolitionism, a movement that would not have emerged for many decades without the animating effects of evangelical religion. Much of this remarkable record has been given short shrift by American historians, who have preferred not to think that religious zealots were behind so many admirable things.

Surely the evangelical left is justified in seeing itself in continuity with that reform history. But so is the evangelical right, which takes so many of its political bearings from the abortion issue. It has long argued that its campaign to change hearts and minds and laws with regard to abortion is the precise equivalent of what faced the abolition movement. In both cases, the task at hand is the humanizing of what had been dehumanized, and the granting of full protection under the law to those who, being fully human, fully deserve such protection, especially in a culture whose religious traditions enjoin the protection of the weak and vulnerable.

But many evangelicals, left and right, have been haunted by the belief that their movement failed at a critical moment in American history. As Donald Dayton put it in his 1976 study, "Evangelical Christianity rather consistently opposed currents of the 1960s that demanded social justice and civil rights." The claim may be exaggerated. The great evangelist Billy Graham was remarkably progressive on matters of race, and major Southern denominations, such as the Baptists and Presbyterians, explicitly supported desegregation. But the weight of the charge is felt, even if the failure was generally more one of passivity than strident opposition. It is a sign of evangelicalism's active conscience that it remains uneasy.

Hence the Promise Keepers movement of the '90s, overwhelmingly an evangelical-right phenomenon, was not only a men's movement but also a movement for racial reconciliation -- a facet entirely missed by hysterical secular critics who were obsessed with its gender dimensions to the exclusion of all else. Hence even within theologically conservative denominations such as the Presbyterian Church in America one finds strenuous efforts to build biracial congregations and support inner-city ministries and missions. Hence the effort by evangelical megachurch pastor Rick Warren, in the presidential forum held at his Saddleback Church on Aug. 16, to promote greater civility in the presidential campaign.

Unfortunately for Sen. Obama, the Saddleback forum turned out to be one of his least effective outings, and his stumbling and evasive remarks about abortion -- the question of life's beginning, he said, was "above my pay grade" -- brought to a sharp point the dilemma faced in this election by all white evangelicals, left, right and center. It would have been one thing to overlook the record of a moderately pro-choice candidate for the sake of racial progress. But the starkness of Sen. Obama's position forces upon evangelicals a profoundly unenviable choice.

And one can be sure that, whatever the election's outcome, recriminations and accusations will be filling the air. One would hope that, at the very least, there would be recognition that some of the evangelical votes against Sen. Obama will be made regretfully, in spite of his race rather than because of it. But that may be too much to hope for in this very un-postracial election.

-- Mr. McClay teaches history and the humanities at the University of Tennessee in Chattanooga.