On Sunday, Billy and Franklin Graham preached to about 33,000 people at Baltimore's Camden Yards. In the audience were the converted, the unconverted and the curious. Oh, and I was there, too.

It was a display of theological power, that's for sure. But it was a display, too, of organizational and financial power and, potentially, political power. And it's the relationship to political power, around the world -- sometimes friendly, sometimes edgy -- that makes the Grahams' story so interesting.

Billy Graham, now 87, has been a force in American life since the 1940s; he has long been atop lists of "most admired Americans." Not surprisingly, he has often been invited to the White House; indeed, although never setting up a political group such as the Moral Majority, he has nonetheless been criticized for being too close to power. Graham's answer has been, in effect, that he would render unto Caesar what was Caesar's, while claiming for God what was God's. That is, the powerful would do what they would, and he would preach as he wished.

On Sept. 14, 2001, Graham joined President George W. Bush and others for a post-9/11 service at the National Cathedral in Washington, D.C., declaring: "Now we have a choice: Whether to implode and disintegrate emotionally and spiritually as a people and a nation -- or whether we choose to become stronger through all of this struggle." And for Graham, the choice was to use the strength that comes from Jesus. Not everyone will agree, of course, and even among those who believe in God, not everyone will agree with Graham's vision; during that brief sermon, he used the words "Jesus," "Christ," "Christian" or "cross" 11 times. Which is to say, Graham was there to do his part as an American to help heal the wounded country, but he was also there as a Christian to preach his gospel.

His son Franklin has continued some of that same nuanced approach to politics. Franklin gave the invocation for Bush's first inauguration, and he has not been afraid to speak his mind about international issues, as when he said, in reference to terrorism, "The God of Islam is not the same God of the Christian or the Judeo-Christian faith. It is a different God, and I believe a very evil and a very wicked religion." One unavoidable element of belief, to be sure, is that if you believe you know The Way, it's hard to think that other Ways are equally valid. Indeed, just about every religion can be found speaking invidiously of just about every other religion.

The point here isn't to try to start up another interfaith feud, but rather to note the obvious: It's usually a sense of unique mission that impels evangelists of all kinds to do what they do, be it saving souls or serving meals. The younger Graham, for example, has spent the past three decades leading a charity called Samaritan's Purse, which has worked on five continents -- including such politically sensitive, not to mention dangerous, places as Darfur, Sudan.

In an impromptu interview with Franklin Graham, I asked him if his group evangelized in officially Muslim countries, such as Pakistan, and officially atheist countries, such as North Korea. He looked at me with the kindly eye of a benevolent teacher trying to help a slow student to learn an obvious point. Yes, of course, was his answer. But first, he said, we deal with their physical needs -- so free food for Pakistani earthquake victims, and tuberculosis testing and treatment in North Korea.

The Grahams, father and son, have worked with political power around the world, to gain access to people -- and to their souls.

What will be the long-term effect of their preaching? Rendering unto Caesar, while focusing on God, is complicated, but it's what the Grahams do, as their torch is passed to a new generation in a new century.