Observers have interpreted Bush's words in different ways.
"This is so conventionally Christian piety and Christian faith that of course it ought not to raise any alarms," said the Rev. Richard John Neuhaus, editor of the Catholic journal First Things. "Any devout Jew, any devout Muslim, also believes God has purposes for his life and tries to divine them. There is nothing that Bush has said about divine purpose, destiny and accountability that Abraham Lincoln did not say. This is as American as apple pie."
But Wallis, the Sojourners editor, said Bush has adopted a "theology of empire" that suggests God is on America's side and confuses the nation with the church.
During Bush's 2003 State of the Union address, for example, he evoked an old gospel hymn when he said, "Yet there's power, wonder-working power, in the goodness and idealism and faith of the American people." What the hymn says, however, is that there is "power, power, wonder-working power in the blood of the Lamb." The hymn, Wallis said, is about the power of Christ -- not the power of the American nation, or any nation.
"It's a good thing, and a normal thing, for religious people to have a sense of calling as a pastor or a teacher or a journalist or a politician. But I think this goes farther," Wallis said. "It's almost a sense of divine appointment for this president and this war on terrorism. . . . When it comes out as 'They're evil and we're good,' and 'If you're not with us on all issues, then you're with the evildoers,' I think it's bad foreign policy and dangerous theology."
As the United States prepared to invade Iraq last year, the mainline Protestant magazine Christian Century said Bush's words and actions also raised the question of whether he shares the view of many evangelicals that history is racing toward an apocalyptic clash and the second coming of Christ.
"Millions of Americans believe that the Bible foretells regime change in Iraq, that God established Israel's boundaries millennia ago, and that the United Nations is a forerunner of a satanic world order," the magazine said in an editorial. "The American people have a right to know how the President's faith is informing his public policies, not least his design on Iraq."
But Bush has not publicly voiced any apocalyptic scenario, and aides scoffed at the notion that he holds one. Neuhaus, who has met several times with the president to discuss abortion and other issues, said that "the whole realm of biblical prophecy . . . with respect to the Middle East" is "quite alien to George W. Bush."
The Rev. Kirbyjon Caldwell, a prominent black minister in Houston and close friend of the president, said Bush is "a mainstream Christian" whose faith is "terminally misunderstood."
"He does not believe God told him to run. He does not believe God told him he would win. He surely does not believe God told him to drop any bombs anywhere in the world," Caldwell said.
A 'Mere Christian'
Recent books on Bush's faith have made the case that his religious beliefs are sincere and that he fits in naturally with evangelicals, in style as well as substance. But none of the authors found it easy to summarize Bush's beliefs.
Aikman, who was given wide access to Bush's friends and senior officials to write "A Man of Faith," said he "could not get from anybody a sort of credo of what [Bush] believes" and was forced to "intuit" many elements of the president's faith. In the end, he said, he concluded that Bush is "a mainstream evangelical with a higher-than-normal tolerance of dissent."
Stephen Mansfield wrote in "The Faith of George W. Bush" that Bush is "a conservative Christian," but added: "On many issues, Bush is less doctrinaire than his faith would make him appear, and this too is part of the mystery of George W. Bush."
Some White House officials suggested that the reason Bush's beliefs seem hard to categorize is not that they are complex and nuanced, but that they are relatively simple and few.
Tim Goeglein, who directs the White House Office of Public Liaison and is the president's official intermediary with Christian groups, said Bush is an evangelical but also fits the Irish theologian C.S. Lewis's definition of a "mere Christian" -- someone who looks beyond denominational lines to the central, common teachings of the universal church.
Frum, the former speechwriter, said: "If you want to know what George Bush really thinks, look at what he says. He believes in a personal god who answers prayers. He believes that truth is found in all religions and that all people who pray pray to the same God. He believes that prayer and faith can allow one to improve one's own life and save one, not just in the theological sense but in this world. And he's told us that he does not ask God to tell him what to do, but asks God for wisdom and judgment and calm. If you said to him, 'Does God want you to invade Iraq?' he'd say, 'I don't know.' He'd say, 'I asked for the best wisdom I could have to make that decision.' "
But if Bush's beliefs are so ecumenical and his prayers so generic, asked the Rev. Shaun Casey, an assistant professor of Christian ethics at the Methodist Church's Wesley Theological Seminary in Washington, do the president's positions on such matters as abortion and same-sex marriage really derive from his faith? And what influence do his religious beliefs have on his budget priorities or tax policies?
Casey, who went to college in West Texas, said he recognizes in Bush an "indigenous West Texas evangelical piety" and thinks "the critics who dismiss him as purely manipulating religion" are wrong.
"The real question is how he moves from this vague constellation of beliefs to specific policies," Casey said. "That's an enigma."