This talent for presenting simple biblical lessons for a suburban age is behind The Purpose-Driven Life, Warren's book detailing his 40-day plan for "Christian living in the 21st century", which is on the shelf of almost every evange­lical household in the US. It has become one of the bestselling non-fiction hardbacks in American history, turning the pastor into a sort of spiritual Oprah, with trademarked books and podcasts and appearances at Wal-Mart. Warren's face has been on the cover of Time; and he was chosen to offer the prayers at Barack Obama's inauguration.

Sixty miles south of Los Angeles, Saddle-back is one of the mega-churches (those with at least 2,000 congregants) that make up the stretch between LA and San Diego known as the "southern Californian Bible Belt". In its grounds, information booths carry maps directing visitors to several white marquees that offer different styles of worship; there are burbling crystal fountains and a baptismal pool that looks like it belongs in an upmarket spa. The teenagers' area, meanwhile, is deliberately scuffed-looking. It contains a big wall display on Aids in Africa - the issue over which Warren has had his greatest impact on evangelicals.

Yet, a year earlier, he had attended a church conference in South Africa with his wife, Kay. She was recovering from cancer and was keen to adopt a big cause. "So we went out to this little village and found this tent church," he has said. "It had 50 adults and 25 kids orphaned by Aids." He has since joined the Bono/Bill Gates philanthropy club, despatching 7,500 volunteers from Saddleback to developing countries. "I'll work with anyone to stop Aids - Christian, Muslim, Jew, atheist," he says. "That really makes the fundamentalists mad."

“Over the past two or three decades, the church became so associated with the Republicans. Now, people are saying: 'Hey, we are for the church - we are not just two-issue people interested in homosexuality and abortion.'" In a 2005 survey of evangelical pastors, 51 percent said that their congregation was predominantly conservative. By 2008, depressed by Bush's unpopularity in his final years, that figure had fallen to 33 per cent.

There is little evidence that evangelicals are any less agitated about abortion, stem-cell research or gay marriage. But since the recession, moral issues have dropped down the priority list. At Saddleback, too much government, not too little, is blamed for California's disastrous financial state. "Government got greedy," a pas­tor in Ray-Bans and a leather jacket tells me, "and started taxing business too much."