No doubt about it, Tony Blair's press secretary delivered a memorable sound bite when a pushy journalist kept asking about faith, politics and the prime minister.

"We don't do God," said Alastair Campbell.

The nosey British press knew better. They knew Blair's staff was discreetly finding him a Catholic pew on Sundays, no matter where his duties took him. Reporters heard insider reports about Blair reading his Bible every night at bedtime, even as he followed a culturally liberal drummer -- pro-abortion rights, pro-gay rights -- in the public square.

But, Blair knew what he was doing, while leading a post-Christian nation next to an even more secular continent. He knew that he couldn't discuss his faith.

"You talk about it in our system and, frankly, people do think you're a nutter," he told BBC after leaving office.

Things have changed since last week's opening of the Tony Blair Faith Foundation dedicated to promoting cooperation among Christians, Muslims, Jews, Hindus, Buddhists and Sikhs. The former prime minister offered a vivid defense of his new work during a recent speech at Westminster Cathedral.

The bottom line: It's impossible to talk about how the world works without facing the power of religion.

"I ... argue that religious faith is a good thing in itself, that so far from being a reactionary force, it has a major part to play in shaping the values which guide the modern world and can and should be a force for progress," he said. "But it has to be rescued on the one hand from the extremist and exclusionary tendency within religion today; and on the other from the danger that religious faith is seen as an interesting part of history and tradition but with nothing to say about the contemporary human condition."

In a follow-up speech, Blair stressed that there is no evidence faith is fading in most of the world. When asked, "Is religion an important part of your life?" between 80 and 90 percent of citizens in Muslim nations say "yes." About 70 percent of Americans agree. What about Europe? A study by the Pew Forum on Religion & Public Life offered blunt numbers. In Great Britain, 33 percent of those polled said religion was "very important," compared with 27 percent in Italy, 21 percent in Germany and 11 percent in France. In other words, Europe is abnormal.

At Westminster, Blair cited several reasons for modern prejudices against faith.

Many Europeans, for example, think believers are weird -- period. They believe politicians who are religious "engage in some slightly cultish interaction" with God before making key decisions. They also assume that believers want to impose their beliefs on others, while pretending that they are "better than the next person," said Blair, who made headlines late last year when he became a Roman Catholic, joining his wife and four children in the church.

"Worst of all," he added, skeptics are convinced believers are "somehow messianically trying to co-opt God to bestow a divine legitimacy" on their politics.

The problem is that it's hard to debate people on the fringes -- religious extremists and militant secularists -- without blurring the lines between faiths that have sharply different beliefs. Blair said that it's crucial to argue that religious believers can tolerate and respect each other without surrendering their own doctrines.

"Let me be clear," he said. "I am not saying that it is extreme to believe your religious faith is the only true faith. Most people of faith do that. It doesn't stop them respecting those of a different faith or indeed of no faith. ... Faith is problematic when it becomes a way of denigrating those who do not share it, as somehow lesser human beings."

Still, it's hard to argue for justice without some core belief that some things are right and some things are wrong. This is one reason, Blair concluded, that very few people want to live and raise their children in a faithless world.

"Faith corrects, in a necessary and vital way, the tendency humankind has to relativism. It says there are absolutes -- like the inalienable worth and dignity of every human being -- that can never be sacrificed. It gives true moral fiber. We err, we do wrong, we sin, but at least we know it and we feel the compunction to do better and the need to seek God?s forgiveness."