WASHINGTON – The descent of the 2016 presidential campaign last week into the realm of sex tapes and marital infidelity was remarkable enough in its own right, but it also offered a reminder of what has been largely absent from the race: a debate about issues of public morality that for decades have been at the heart of the country's political divide.

 In a striking departure from the recent history of White House campaigns, there has been almost no discussion of abortion or gay rights, two of the most animating issues for millions of American voters.

“This is more about this year’s candidates than it is about the country,” said Russell Moore, the public face of the Southern Baptist Convention. “I don’t think America is as secular as this campaign would have you think.”

The country may get a reminder of that Tuesday evening during the vice-presidential debate.

The two men who will face off, Sen. Tim Kaine of Virginia and Gov. Mike Pence of Indiana, share a deep religious faith that is central to their politics, but has been obscured by a more profane than holy race on top of the ticket.

While both men are devout, they represent different strands of Christianity in American life, a contrast that is likely to be on display as they discuss their positions on social issues and how religious beliefs would guide their approach to governing.

Pence, who was raised Catholic, turned toward evangelical Christianity when he was in college and has made no secret of how cultural issues have shaped his politics. He was one of the most outspoken foes of abortion rights and same-sex marriage when he was Congress. And as Indiana’s governor, he became engulfed in controversy after he signed legislation allowing the state’s business owners to deny services to gay, lesbian and transgender people for religious reasons.

But Pence, whose signature line is that he is “a Christian, a conservative and a Republican — in that order,” finds himself in a campaign devoid of any debate about the moral questions that have for decades been central to the country’s right-left political divide.

Kaine, who like Pence has Irish roots and was raised Catholic, had his faith forged when, during law school, he went to Honduras and served as a missionary for the Jesuits. It was there that he embraced a brand of liberation theology centered on social justice that would eventually be one of the forces propelling him into government.

Early in his political career, Kaine’s style of Catholicism made him uneasy with some elements of the Democratic Party, particularly on issues like abortion rights and same-sex marriage. While he has since shifted on those issues to accommodate his party — and his running mate — he remains unapologetic about how important his faith is to his career in public service.

“I’ve been very plain about my time in Honduras and about how important my own spiritual life is to me as my big motivator in this,” Kaine said in an interview.

He said he had not encountered any discomfort from his party, which polls show to be increasingly secular, when he talks about his religious beliefs.

“It doesn’t divide you from people,” he said. “It actually connects you to people because they’re skeptical about people in politics but curious about us, too, and if you share with them what motivates you, that gives them some understanding of who you are.”

But the openness with which the vice-presidential candidates discuss religion, and their focus on moral issues, have not been shared by their partners atop the ticket.

Donald Trump, who has been married three times and boasted of his affairs, does not discuss matters of sexual morality, even when speaking to Christian conservatives. In a break from recent Republican nominees, Trump did not mention abortion or even allude to the sanctity of life a single time in his marathon acceptance speech at this summer’s Republican National Convention.

Hillary Clinton prefers to draw attention to Trump’s statements on race and gender, painting him as an outlier from his own party rather than, in the fashion of most Democratic presidential candidates, linking him to the Republican Party’s hard-line social platform.

And some people of faith have been frustrated by the fact that the issues they have fought over for years are all but missing from the campaign. Oran Smith, who heads South Carolina’s Palmetto Family Council, said he was reminded of the old line about Christian conservatives and the Republican Party: “We’re on the bus, we’re just not driving the bus.”

He said this election demonstrated why evangelicals need to be more assertive in Republican politics, urging them to “take over the party infrastructure,” at least in early-voting Iowa and South Carolina.

For now, though, people of faith are choosing between two candidates uneasy discussing religion.

Trump has at times been unable to cite a single Bible verse and memorably referred to the second book of Corinthians as “Two Corinthians,” a sign of his unfamiliarity with Scripture. Clinton is a Methodist and more grounded in the church, but she concedes that discussing her own faith does not “come naturally.”

The candidates at the top of the ticket are not exactly ignoring faith-based voters, however. Clinton is relying on black churchgoers, a key constituency in her primary victory this year, and Trump has consolidated support among white evangelicals thanks to a determined courtship, a pledge to appoint conservative judges and their fear of four more years of a Democrat in the White House.

“This is an easy election,” said Jerry Falwell Jr., president of Liberty University and one of Trump’s earliest evangelical supporters. “If you’re a pro-life Christian, you know Hillary Clinton is going to appoint justices who are not pro-life.”

To other conservative Christians, though, the choice is more agonizing than easy.

“Any way I look at this I lose,” said Moore of the Southern Baptist Convention, comparing Clinton’s social liberalism with what he called Trump’s “Howard Stern conservatism.”

Evangelicals like Smith are troubled by Trump’s divorces, inflammatory language about gender and race and his lack of repentance in public. And among such voters there is uncertainty about whether, given his lack of a track record, they can trust Trump’s promises on judges and his vows to strip federal funding from Planned Parenthood and protect what conservatives call religious liberty.

That a number of leading evangelicals and so many in the rank-and-file lined up with Trump only points to how willing they are to toe the party line, Moore said. “The Republican Party assumes it can count on conservative Christians no matter what,” he said. “And this election seems to be proving that theory right.”

Yet veterans of evangelical politics who have embraced Trump point to a body of evidence they say indicates he will fulfill his commitments to them after working relentlessly to win over Christian conservatives, speaking at their gatherings, inviting them to Trump Tower and seeking their counsel.

“I can’t think of a nominee of this party since Reagan in 1980 who has more aggressively courted the evangelical vote than Donald Trump,” said Ralph Reed, a longtime Republican consultant.

Wooing aside, though, many conservative evangelicals wish they simply had better options. Like the two gentlemanly Christians much of the country will see for the first time Tuesday.

“If we had a Mike Pence vs. Tim Kaine race, it would be an election worthy of the American people,” Moore said.