Blair, a former Anglican who became a Catholic in 2007 -- less than a year after he stepped down from leading his country for a decade -- said that faith was vital because it introduced the virtue of humility into societies.

"What is the essence of our faith besides all the things we believe, certainly as Christians, about Jesus Christ and his place in our lives?" he asked.

"It is also fundamentally a belief that there is something bigger and more important than you, that you are not the only thing that matters, that there is something that is greater and transcendent," he told the leadership conference organized by the Holy Trinity Brompton, an influential Anglican parish in London.

"I think that essential obligation of humility for humanity is deeply important," he said. "It is what allows us to make progress, it is what keeps us from ideology or thought processes that then treat human beings as if they were secondary to some political purpose."

He said: "For a long period of time, what people thought was that as society became more developed and as we became more prosperous, that faith would be relegated, that it would become a kind of relic of the past -- what kind of ignorant people do but not what civilized, educated people do.

"I think a world without faith would be a world on the path to tragedy and disaster, I really believe that," he added.

The former Labor Party leader acknowledged that "God and religion can also be abused by politicians" and said it was important to be cautious of those who might be using religion for their own purposes.

But he said that when he proposed to finish a speech as prime minister simply with the words "God bless Britain," an aide told him disapprovingly: "I just remind you Prime Minister, this is not America."

He said he then abandoned the idea.