That was especially notable Sunday night, when Democrats Hillary Clinton and Barack Obama appeared at a nonpartisan forum on religious faith, politics and public policy that was co-sponsored by CNN and the group Faith in Public Life. The so-called "Compassion Forum" wasn't a debate. Obama and Clinton answered questions separately, but those questions came from prominent religious leaders – many of them evangelicals.

McCain was invited to the event at Messiah College in Grantham, Pennsylvania. And frankly the candidate who has struggled to connect with the Grand Old Party's evangelical base could have done himself some favors by participating in a forum that lived up to its promise to produce "wide-ranging and probing discussions of policies related to pressing moral issues that are bridging ideological divides now more than ever, including poverty, global AIDS, climate change and human rights."

But McCain, who will be campaigning in Pennsylvania this week, could be bothered to participate in the "Compassion Forum." If McCain really believes in keeping religion private, more power to him; in fact, such a stance would be a selling point for his campaign. But if his campaign plans to run a back-channel campaign to exploit evangelicals as a voting bloc -- as everyone expects -- but just wanted to avoid a forum where he would have been compared with Obama and Clinton, then this is one more example of how the presumptive Republican nominee's "Straight-Talk Express" is misnamed.

For their parts, Clinton and Obama were predictably faithful, expressing their views in terms familiar to followers of mainstream liberal Christianity – which both candidates profess, rather more loudly than the founders might have expected of candidates for the highest office in country where the division between church and state is supposed to be a strong one.

Clinton says she believes literally in the resurrection of Jesus Christ as a historical fact, and claims to have felt the presence of the Holy Spirit. "I have, ever since I was a little girl, felt the presence of God in my life," she told interviewer Campbell Brown on Sunday night, adding that, "I don't think I could have made my life's journey without being anchored in God's grace."

The only part of the evening when she was not exactly graceful came when she went after Obama for suggesting that some small-town voters are "bitter" individuals who cling "to guns or religion or antipathy to people who aren't like them or anti-immigrant sentiment or anti-trade sentiment as a way to explain their frustrations."

"You know, the Democratic Party, to be very blunt about it, has been viewed as a party that didn't understand and respect the values and the way of life of so many of our fellow Americans," Clinton said Sunday night. "And I think it's important that we make clear that we believe people are people of faith because it is part of their whole being; it is what gives them meaning in life, through good times and bad times."

Obama, who has campaigned as a "committed Christian" and distributes literature showing him at a pulpit, in front of a cross, was equally blunt in his discussion of his religious experience. And he was adept in countering Clinton's suggestion that he's an elitist. While he may have chosen some words poorly, Obama stuck to his core point that: People turn bitter because the experience of contemporary politics leaves them without "any confidence that the government is listening to them."

"Scripture talks about clinging to what's good," he said. "And so it's very important -- my words may have been clumsy, which happens surprisingly often on a presidential campaign -- but this is something that I've talked about before, I've talked about in my own life, which is that religion is a bulwark, a foundation when other things aren't going well," said Obama. "That's true in my own life, through trials and tribulations. And so what I was referring to was in no way demeaning a faith that I, myself, embrace. What I was saying is that when economic hardship hits in these communities, what people have is they've got family, they've got their faith, they've got the traditions that have been passed onto them from generation to generation. Those aren't bad things. That's what they have left."

Ultimately, both Obama and Clinton handled the forum with grace – even the questions about what Clinton referred to as "that very difficult question" of whether life begins at conception.

Clinton got off the best line of the night. Asked why a loving God allows so much suffering, she replied, "I don't know. I can't wait to ask him." That got a loud laugh, just as her suggestion that the suffering of the poor should be seen as "a call to action." "Maybe the Lord is just waiting for us to respond to His call," added Clinton, in what was arguably one of the finer moments of the campaign for her.

Clinton was "on" Sunday night.

Obama was at his best.

But where was John McCain?